Pharmaceutical compounds, their preparation and use.

This invention relates to ethers useful in medicine, to the preparation of such compounds, to pharmaceutical formulations containing such compounds and the preparation of such formulations, to the use of the compounds in medicine, and to novel intermediates for the said compounds and the preparation thereof.

The present invention more particularly relates to the novel ether compounds of formula (I), <chemistry id="chem0001" num="0001"><img file="EP0054924A2_D0001.tif" /></chemistry>as hereinafter defined, which are of value in medicine in the palliation of haemoglobinopathies including and in particular sickle-cell anaemia.

Sickle-cell anaemia is essentially a disease of childhood. The major manifestations are a chronic haemolytic anaemia and vaso-occlusive crises that cause severe pain as well as long-term and widespread organ damage. In addition there are systemic effects such as increased susceptibility to infections and impaired growth and development.

The behaviour of the haemoglobin (predominantly "sickle haemoglobin", referred to as Hb-S) in erythrocytes (red blood cells) from sickle-cell anaemia sufferers differs from that of the haemoglobin in erythrocytes from normal adults (predominantly the Hb- A form) in the following important aspects. <ul id="ul0001" list-style="none"><li>(A) The oxygen - dissociation curve. When a graph is plotted of the percentage saturation of haemoglobin with oxygen (ordinate) against the partial pressure of oxygen, sometimes called the oxygen tension (abscissa) a characteristic sigmoid curve is obtained. With respect to the curve obtained with whole blood from normal adults, that obtained with whole blood from sickle-cell anaemia sufferers is displaced to the right. That is to say, the haemoglobin in the sickle-cell erythrocytes has a reduced oxygen affinity compared with that in the normal erythrocytes, a higher oxygen tension being required to produce a given percentage saturation.</li><li>(B) The deoxyhaemoglobin tetramer. When erythrocytes from sickle-cell anaemia sufferers are deoxygenated in vitro under physiological conditions the Hb-S therein aggregates into long 'pol^ymers', non-covalently linked arrays of deoxyHb-S molecules which align themselves into viscous paracrystalline gels. This deoxygenation-dependent gelation is accompanied by deformation of the erythrocyte (commonly termed sickling) into characteristic sickle and holly-leaf forms and by a loss of deformability. No such behaviour is observed with erythrocytes from normal adult individuals. The gelation and sickling can be reversed by oxygenation, ie. conversion of the deoxyHb-S to the oxygenated conformation, except for a proportion identified as irreversibly sickled cells (I8C's) which are characterised by their inability to resume the normal biconcave disc shape even after dissolution of the Hb-S gel.</li></ul>

Although the exact relationships are as yet incompletely understood the gelation, sickling and loss of deformability are known to be involved in the pathophysiology of the disease : typically between 30 and 60 per cent of the erythrocytes in venous blood from sickle-cell anaemia sufferers are sickled.

Because it has its origins in a genetic defect no true cure for sickle-cell anaemia is possible short of genetic manipulation. At present, effective medical intervention is restricted to supportive care, treatment of infections and therapies directed towards particular organ involvement. The prime objective of much current research is a drug that will compensate for the fundamental defect of sickle-cell anaemia but as yet no compound has proved to be both sufficiently efficacious and safe to be generally acceptable (for a review see 'Sickle-cell anaemia : Molecular and cellular bases of therapeutic approaches' by J Dean and A N Schechter, New England Journal of Medicine, 299 (1978) pp 752-763, 804-811 and 863-870).

The compounds of formula--(I), as hereinafter defined, are effective in the palliation of sickle-cell anaemia (ie. in alleviating the symptoms of the disease and in mitigating the sufferings of those having the condition) and in particular exhibit the following properties: <ul id="ul0002" list-style="none"><li>(A) They induce a left-displacement of the oxygen-dissociation curve of whole normal (AA genotype) human blood in vitro, ie. the oxygen affinity is increased and the oxygenated conformation of the Hb-A is stabilized.</li><li>(B) They induce a left-displacement in vivo of the oxygen-dissociation curve of whole rat blood.</li><li>(C) They prevent the onset of sickling in vitro in whole homozygous (SS genotype) human sickle-cell blood.</li></ul>

In formula (I)<img file="EP0054924A2_D0002.tif" /><ul id="ul0003" list-style="none"><li>Y is selected from hydroxyl, alkylamino of 1 to 4 carbon atoms and alkanoylamino having 1 to 4 carbon atoms in the alkyl moiety thereof;</li><li>Y²Y³and Y⁴ are independently selected from hydrogen, halogen, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, trifluoromethyl, hydroxyl and benzyloxy; and</li><li>_Q¹ is either <chemistry id="chem0002" num="0002"><img file="EP0054924A2_D0003.tif" /></chemistry>where</li><li>Q² and Q³ are independently selected from hydrogen and alkyl of 1 to 4 carbon atoms;</li><li>X is selected from cyano, carb^pxyl or a derivative thereof, 5-tetrazolyl and alkylsulphonylcarbamoyl having 1 to 6 carbon atoms in the alkyl moiety thereof; and</li><li>n is 0 or an integer selected from 1, 2, 3, 4, 5 and 6;</li></ul> together with salts thereof, provided that <ul id="ul0004" list-style="none"><li>when Y¹is hydroxyl, _Y², _Y³ and _Y⁴ are all hydrogen and Q¹ is either <chemistry id="chem0003" num="0003"><img file="EP0054924A2_D0004.tif" /></chemistry></li><li>then X is alkylsulphonylcarbamoyl.</li></ul>

The halogen identities for Y², Y³ and Y⁴ may be selected from iodine, bromine, chlorine and fluorine.

The al kyl identities for Q² and Q ³ preferably have 1 or 2 carbon atoms (ie. methyl or ethyl) and are desirably methyl.

Compounds within formula (I) wherein X is a carboxyl derivative include: <ul id="ul0005" list-style="none"><li>esters, including aliphatic and aromatic hydrocarbon esters such as alkyl and aralkyl esters where for example the alkyl has 1 to 12 and preferably 1 to 4 carbon atoms (in particular methyl, ethyl, isopropyl and t-butyl) and where the aralkyl is for example benzyl; and</li><li>amides, including the unsubstituted amide, N-substituted amides and N, N-disubstituted amides (embracing cyclic and heterocyclic amides) where the substituent group(s) is (are) for example aliphatic hydrocarbon such as alkyl, in particular alkyl of 1 to 4 carbon atoms such as methyl, ethyl, isopropyl and t-butyl.</li></ul>

In the salts of the compounds of formula (I) the biological activity resides in the ether (anion) moiety and the identity of the cation is of less importance although for use in medicine it is preferably pharmacologically acceptable to the recipient. Suitable salts include ammonium salts, alkali metal salts such as sodium and potassium salts, and salts formed with organic bases.

Compounds of formula (I) wherein Y is alkylamino can form acid addition salts; in such salts the biological activity resides in the ether moiety and the identity of the acid is of less importance although for use in medicine it is preferably pharmacologically acceptable to the recipient. Suitable acids are well known in the art, for example hydrochloric acid and acetic acid.

As a subcia within formula (I) may be mentioned the compounds wherein <ul id="ul0006" list-style="none"><li>X is selected from cyano, 5-tetrazolyl, alkylsulphonylcarbamoyl having 1 to 6 carbon atoms in the alkyl moiety thereof and a group - CO. Y, where</li><li>Y is -OR¹and R¹ is hydrogen, alkyl of 1 to 4 carbon atoms or benzyl, or</li><li>_Y is -NR²R³ where R² and R³are independently hydrogen or alkyl of I to 4 carbon atoms,</li></ul> together with salts thereof.

Preferred within formula (I) are those compounds wherein X is carboxyl, together with salts thereof.

A particular preferred compound is <chemistry id="chem0004" num="0004"><img file="EP0054924A2_D0005.tif" /></chemistry>chemically named 4- (2-formyl-3-hydroxyphenoxymethyl)benzoic acid, together with salts thereof.

Where the compounds of formula (I), as above defined, include an asymmetric centre the said formula should be understood to include all optical isomers embraced thereby and mixtures thereof.

The compounds of formula (I) and their salts may be prepared by those methods known in the art for the synthesis of compounds of analogous structure and in this regard reference is made, by way of illustration only, to the following standard texts:- <ul id="ul0007" list-style="none"><li>(i) "Protective Groups in Organic Chemistry", ed. J. F. W. McOmie, Plenum Press (1973), ISBN 0-306-30717-0;</li><li>(ii) "Compendium of Organic Synthetic Methods", ed. I. T. Harrisonr and S. Harrison, Wiley-Interscience, Vol. I (1971) ISBN 0-471-35550-X, Vol. II (1974) ISBN 0-471-35551-8 and Vol. III (ed. L. S. Hegedus and L. Wade) (1977) ISBN 0-471-36752-4; and</li><li>(iii) Rodd's "Chemistry of Carbon Compounds", second edition, Elsevier Publishing Company.</li></ul>

All references identified hereinabove or in the following are hereby incorporated herein by reference thereto.

(1) One method comprises reaction of the phenol (II) with an alkane derivative (III) <chemistry id="chem0005" num="0005"><img file="EP0054924A2_D0006.tif" /></chemistry>wherein Y¹, Y², Y³, Y⁴ and Q¹ are as defined in formula (I) and Z¹ is a leaving atom or group.

As one possibility Z¹ is selected from for example halo (such as bromo, when a catalytic amount of for example sodium iodide is desirably present), arylsulphonyloxy such as p-toluenesul- phonyloxy and alkylsulphonyloxy such as methane- sulphonyloxy, the reaction being carried out under basic conditions.

The reaction may thus for example be effected in the presence of an alkali metal carbonate such as potassium carbonate, an alkali metal alkoxide such as sodium or potassium ethoxide or an alkali metal hydride such as sodium hydride and in a solvent such as a lower alkanol (for example, ethanol) or an aliphatic ketone (for example, acetone or methylethylketone), and is conducted at elevated temperatures, preferably at the reflux temperature of the reaction mixture. As an alternative, the alkali metal hydride may be employed at ambient temperature in a solvent such as dioxan, tetrahydrofuran, dimethylsulphoxide, acetonitrile, dimethylformamide or dimethylacetamide.

In an alternative procedure (II) is reacted in the presence of triphenylphosphine and diethyl azodicarboxylate with a compound (III) having Z as hydroxyl, the reaction being conducted under an inert atmosphere (for example nitrogen or argon) and in a polar aprotic medium.

(2) For compounds wherein Y¹ is hydroxyl, a further method comprises conversion of an ether (IV) <chemistry id="chem0006" num="0006"><img file="EP0054924A2_D0007.tif" /></chemistry> wherein Y², y³, Y and Q¹ are as defined in formula (I), -OZ is hydroxyl or a group convertible thereto and Z³ is formyl or a group convertible thereto and where Z³ is other than formyl when -OZ² is hydroxyl, or -OZ² and Z³ together comprise a ring system that can be selectively cleaved to provide the o-hydroxy-formyl function.

Suitable identities for the moiety Z² include alkyl, for example alkyl of 1 to 4 carbon atoms and in particular methyl, ethyl, isopropyl and t-butyl; aralkyl such as benzyl; acyl such as alkanoyl, in particular alkanoyl where the alkyl moiety therein methoxymethyl; has 1 to 4 carbon atoms, for example acetyl; methoxyethoxymethyl; and tetrahydropyranyl. Such groups may be removed, i.e. replaced by hydrogen, by methods standard in the art. Thus removal of an alkyl group may be effected using for example magnesium iodide or sodium thiocresolate or (at reduced temperatures) by use of an agent such as or tribromide boron trichloride in a medium such as dichloromethane; an acyl group may be removed by base methoxymethyl, hydrolysis; an alkyl group, methoxyethoxymethyl and tetrahydropyranyl may be removed by acid hydrolysis; and hydrogenolysis (for example using a palladium charcoal catalyst) may be used to remove an aralkyl group.

Suitable identities for Z³ include conventional protecting groups for aldehydes such as acetal, thioacetal (mercaptal), oxime, hydrazone (including phenylhydrazone), semicarbazone and anil (Schiff base) functions. The formyl group can be generated therefrom by standard procedures, for example by acid or base hydrolysis or, in the case of thioacetals, by treatment with mercuric chloride in the presence of cadmium carbonate.

As further possible identities for Z³ may be mentioned groups selectively oxidisable to the formyl group. Thus when Z³ is methyl the compound of formula (I) may be obtained by use of chromium trioxide in acetic anhydride with subsequent hydrolysis (for example dilute sulphuric or hydrochloric acid) of the initially formed benzylidene acetate; when Z³ is -CH₂0H suitable reagents include chromium trioxide in pyridine, pyridinium dichromate, pyridinium chlorochromate and manganese dioxide. Other suitable procedures include treatment of the corresponding benzylidene chloride (Z is -CHC1₂) either with water at elevated temperatures and in the presence of iron powder as catalyst or with boric acid. The compounds of formula (I) may also be derived from the corresponding benzyl chloride (Z is -CH₂C1) by refluxing with aqueous copper or lead nitrate in a current of carbon dioxide or alternatively by refluxing with hexamethylenetetramine in aqueous ethanolic solution (Sommelet's reaction).

Further suitable techniques comprise selective reduction to the formyl group of appropriate identities for Z³. In particular may be mentioned reduction of the benzoyl chloride (Z³ is -COC1) using hydrogen and a palladium catalyst in the presence of a quinoline-sulphur poison (Rosenmund's reduction); reduction of the nitrile (Z³ is -CN) using Raney nickel in formic acid, stannous chloride and hydrochloric acid (Stephen's method) or a reagent such as sodium triethoxyaluminium hydride, prepared from aluminium ethoxide and sodium hydride in ether or tetrahydrofuran; and reduction of an alkyl (for example methyl or ethyl) ester (Z³ is -COOMe/Et) by use of sodium diisobutylaluminium hydride (from sodium hydride and diisobutylaluminium hydride) in ether at -70°C.

As another possibility, an ether (IV) wherein z³ is the 4-oxazolinyl group may be converted into a compound of formula (I) by treatment with an alkyl iodide, for example methyl iodide, to yield the quaternary N-alkyl compound followed by reduction with an agent such as sodium borohydride.

Suitable compounds within formula (IV) wherein -OZ² and Z³ together comprise a ring system as above defined include the benzofurans (V) and the 1,3-benzodioxans (VI) <chemistry id="chem0007" num="0007"><img file="EP0054924A2_D0008.tif" /></chemistry>wherein (in (V))Y ⁵ is selected from hydrogen, alkyl (1 to 4 carbon atoms), aryl (for example phenyl), aralkyl (for example benzyl), alkanoyl having 1 to 4 carbon atoms in the alkyl moiety thereof, aranoyl (for example benzoyl) and alkanoxycarbonyl having 1 to 4 carbon atoms in the alkyl moiety thereof and (in (VI)) Z⁴ is lower alkyl such as methyl or ethyl. Conversion of the Benzofurans to the compounds of formula (I) may be effected by ozonolysis and subsequent treatment with dimethylsulphide or with zinc dust in acetic acid, or by chromic acid hydrolysis. Where ozonolysis is effected of a benzofuran having Y⁵ as alkyl, aryl or aralkyl, saponification of the (open-ring) product thereof will be required to remove said group, conveniently by use of aqueous sodium or potassium hydroxide. Conversion of the 1,3-benzodioxans to the compounds of formula (I) may be effected by acid hydrolysis.

(3) For compounds of formula (I) and salts thereof wherein Q¹ is a group <chemistry id="chem0008" num="0008"><img file="EP0054924A2_D0009.tif" /></chemistry>a further method comprises selective reduction of an ether (VII) <chemistry id="chem0009" num="0009"><img file="EP0054924A2_D0010.tif" /></chemistry>wherein Y¹, Y², Y³, Y⁴ and X are as defined in formula (_I) and -Z⁵- is a group selectively reducible to <chemistry id="chem0010" num="0010"><img file="EP0054924A2_D0011.tif" /></chemistry>

As one possibility -Z⁵- may be an unsaturated hydrocarbon chain which includes a vinylene or ethynylene group, as in respectively for example <chemistry id="chem0011" num="0011"><img file="EP0054924A2_D0012.tif" /></chemistry>Such groups may be reduced by methods standard in the art, for example a vinylene group by use of hydrogen and a catalyst such as palladium, Raney nickel or Adams' catalyst, while Adams' catalyst may also be used in respect of an ethynylene group.

As another possibility -Z⁵- may include an oxo group, as in for example <chemistry id="chem0012" num="0012"><img file="EP0054924A2_D0013.tif" /></chemistry>which may be reduced to a methylene group by standard procedures such as the Clemmensen reduction using amalgamated zinc and concentrated hydrochloric acid or by heating with concentrated hydriodic acid and red phosphorus. It will be appreciated that in such circumstances the formyl group in the starting material (VII) may require initial protection and subsequent deprotection for example in the manner indicated in (2) supra.

(4) The compounds of formula (I) and salts thereof may also be prepared by introduction of a formyl group into an ether (VIII) <chemistry id="chem0013" num="0013"><img file="EP0054924A2_D0014.tif" /></chemistry>wherein Y¹, Y², Y³, Y⁴ and Q are as defined in formula (I)_.

As one possibility this may be effected by lithium exchange with an agent such as phenyllithium and subsequent formylation with for example dimethylformamide, N-methylformanilide or diethylphenyl orthoformate.

As an alternative procedure, those compounds of formula (I) wherein (in the group Q¹) X is a group stable under basic conditions (for example, carboxyl and 5-tetrazolyl) may be prepared by the Reimer-Tiemann synthesis, i.e. reaction with chloroform and a base such as pyridine or an alkali metal hydroxide or carbonate.

(5) A further method comprises conversion of a compound of formula (IX) <chemistry id="chem0014" num="0014"><img file="EP0054924A2_D0015.tif" /></chemistry>wherein Y¹, Y², Y³ and Y⁴ are as defined in formula (I), Z⁶is a group convertible to a group X as defined in formula (I) and -Q⁴- is selected, as appropriate, from <chemistry id="chem0015" num="0015"><img file="EP0054924A2_D0016.tif" /></chemistry>

Thus the compounds of formula (I) having X as the 5-tetrazolyl group may be prepared by reacting a compound of formula (IX) wherein Z⁶ is a tetrazolyl group precursor with hydrazoic acid or a salt thereof or with nitrous acid, as appropriate.

Compounds of formula (IX) wherein Z⁶ is formyl, -CH_ZOH or (lower alkyl) alkanoyl such as acetyl may be converted to the carboxyl compounds of formula (I) (X is carboxyl) by standard oxidative procedures using for example acid dichromate: it will be appreciated that in such circumstances the formyl group present in (IX) and retained in the compound of formula (I) may require initial protection and subsequent deprotection, for example-in the manner indicated in (2) supra. The acetyl compounds of formula (IX) may also be converted to the carboxyl compounds of formula (I) by means of the haloform reaction. The said carboxyl compounds may also be prepared by hydrolysis of the corresponding acid chlorides and (lower alkyl) mixed anhydrides such as the ethyl compounds (Z⁶ is -CO.O.CO.Et).

The (lower alkyl) mixed anhydrides of formula (IX) and the acid chlorides may be converted to the esters within formula (I) by reaction with the appropriate alcohol while the amides within formula (I) may be prepared by ammonolysis of the said starting materials using ammonia or a primary or secondary amine, as appropriate.

It will be appreciated that this synthetic approach also embraces the conversion, by standard procedures, of certain of the end-product compounds of formula (I) to other compounds also within the said formula. Thus the esters may be converted to the corresponding carboxyl compounds (carboxylic acids) by hydrolysis, the corresponding salts being obtained when the hydrolysis is carried out with alkali (saponification), and to the amides by ammonolysis using, as appropriate, ammonia or a primary or secondary amine. The amides may also be prepared by treatment of the carboxyl compounds with for example triethylamine and ethyl chloroformate followed by, as appropriate, an ammonium salt or a primary or secondary amine. The unsubstituted amides may also be prepared by treating an ester with sodamide in liquid ammonia, by the action of heat upon the ammonium salts of the carboxylic acids, or by reacting the said acids with urea. The acids and, as appropriate, salts thereof may be prepared by acid or base, preferably base, hydrolysis of an-amide or by the action of nitrous acid upon the unsubstituted amides. The esters may be obtained from the acids by esterification using the appropriate alcohol or, for alkyl esters having at least two carbon atoms, by treatment with the appropriate olefin in the presence of boron trifluoride. The alkyl esters may also be prepared by refluxing the silver salts oi the acids in ethanol with the appropriate alkyl halide, while the methyl esters may specifically be prepared by treating the acids with diazomethane in ether. Conversion of the benzyl esters to the acids.may be effected by hydrogenolysis using for example a palladium charcoal catalyst and conversion of one ester to another is possible using routine transesterification techniques.

The nitriles of formula (I) (X is cyano) may be converted by conventional hydrolysis procedures to the carboxylic acids (X is carboxyl) or, by graded hydrolysis, to the corresponding unsubstituted amides. The said nitriles may also be converted to the corresponding 5-tetrazolyl compounds of formula (I) by reaction with hydrazoic acid or a salt thereof (vid. sup.), the reaction preferably being carried out at elevated temperature with a hydrazoic acid salt such as the ammonium salt and in a polar aprotic medium such as dimethylsulphoxide or dimethylformamide.

Compounds of formula (I) wherein X is alkylsulphonylcarbamoyl may be prepared by reacting a (lower alkyl) mixed anhydride of formula (IX) (for example the ethyl or isobutyl compound) with an alkali metal salt of the appropriate alkanesulphonamide, the latter reagent being conveniently prepared in situ by for example reacting the alkanesulphonamide with sodium methoxide in methanol. The mixed anhydride starting material may be prepared by methods analogous to those well known in the art, for example from the corresponding carboxylic acid and a (lower alkyl) chloroformate in the presence of triethylamine or N-methylmorpholine and in a solvent such as tetrahydrofuran.

(6) For compounds wherein at least one of Y², Y³ and Y⁴ is hydrogen, a further method comprises decarboxylation of a benzoic acid (X) <chemistry id="chem0016" num="0016"><img file="EP0054924A2_D0017.tif" /></chemistry>wherein Y and Q¹ are as defined in formula (I) and one of Z⁷, Z⁸ and Z⁹ is carboxyl and the other two have the same meanings as respectively Y², _Y³ and Y ⁴ also as defined in formula (I).

The decarboxylation may be effected by any of the conventional techniques, for example by heating (X) in quinoline in the presence of copper or with dioxane and acidic alumina.

(7) For compounds wherein Y is alkylamino or alkanoylamino, a further method comprises conversion of an ether (XI) <chemistry id="chem0017" num="0017"><img file="EP0054924A2_D0018.tif" /></chemistry>wherein Y² , Y³, Y⁴ and _Ql are as defined in formula (I), -NHZ¹⁰ is alkylamino or alkanovlamino as defined in formula (I) and Z³is a group convertible to formyl (for compounds wherein Y¹ is alkanoylamino) -NHZ¹⁰ and _Z³ together comprise a ring system that can be selectively cleaved to provide an o-alkanc lamino- formyl function.

Suitable identities for Z³together with appropriate procedures for generating the formyl group therefrom are as recited supra.

Suitable compounds within formula (XI) wherein -NHZ ¹⁰ and _Z³ together comprise a ring system as above defined include the indoles (XII) <chemistry id="chem0018" num="0018"><img file="EP0054924A2_D0019.tif" /></chemistry>wherein Z11 is alkyl of 1 to 4 carbon atoms. Conversion of the indoles to the compounds of formula (I) may be effected by ozonolysis and subsequent treatment with dimethylsulphide or with zinc dust in acetic acid, or by chromic acid hydrolysis.

(8) A further method comprises conversion of a compound of formula (XIII) <chemistry id="chem0019" num="0019"><img file="EP0054924A2_D0020.tif" /></chemistry>wherein Y¹ and Q¹ are as defined in formula (_I) and at least one of _Z¹², _Z¹³ and Z¹⁴ is an atom or group replaceable by or convertible to respectively Y², Y³ or Y⁴ as defined in formula (I) and the other(s), if any, of Z¹², Z¹³ and Z14 are respectively Y , Y or Y⁴.

Thus as one possibility a hydrogen atom may be replaced by an alkyl group by means of the Friedel-Crafts reaction using an alkylating agent (conveniently an appropriate alkyl halide, for example the chloride) and a catalyst such as aluminium chloride, stannic chloride or boron trifluoride. A t-butyl group may also be introduced by reaction with t-butanol in the presence of an acid catalyst such as concentrated phosphoric acid.

A hydrogen atom may be replaced by a halogen by conventional techniques. Thus chlorination may be effected using for example t-butyl hypochlorite in acetic acid whilst iodination may be conducted using for example either iodine monochloride or iodine and potassium iodide in solution in concentrated ammonia.

Suitable precursors for a hydroxyl group are groups - OZ² where Z² has the identities recited supra, the hydroxyl group being generated therefrom by procedures as previously described herein. Within this generality may particularly be mentioned the conversion, in the manner described, of alkoxy and benzyloxy groups to the hydroxyl group. Conversely a hydroxyl group may be converted to an alkoxy or benzyloxy group by reacting an <img file="EP0054924A2_D0021.tif" />in a manner analogous to that described in respect of method (1) supra, with a compound Z¹-Z¹⁵ wherein _Z¹ is as previously defined and Z¹⁵ is respectively alkyl or benzyl.

The compounds of formula (I) wherein X is carboxyl or 5- tetrazolyl may be isolated as such or as salts thereof and it will be appreciated that the said compounds may be converted to salts thereof, and the reverse, and the salts converted to salts formed with other cations, by techniques well-known and conventional in the art. Thus, those salts which are not themselves pharmacologically acceptable are of value in the preparation of the parent carboxyl or 5- tetrazolyl compounds and of pharmacologically acceptable salts thereof. Similarly, addition salts of appropriate compounds of formula (I) with non-pharmacologically acceptable acids may be used in the preparation of the parent ethers and of pharmacologically acceptable acid addition salts thereof.

When the preparative procedures herein described provide a mixture of optical isomers of a compound of formula (I) or of an intermediate thereto, the individual isomers may be separated by appropriate conventional techniques.

The compounds of formula (I), as above defined, may be used in medicine in the palliation of haemoglobinopathies and in particular for alleviating the symptoms of sickle-cell anaemia and mitigating the sufferings of those having the condition. The compounds may be used both on a regular maintenance basis and for the relief of acute crisis states.

The compounds may be administered to the human recipient by a route selected from oral, parenteral (including subcutaneous, intradermal, intramuscular and intravenous) and rectal. The size of an effective palliative dose of a compound will depend upon a number of factors including the identity of the recipient, the type of haemoglobinopathy involved, the severity of the condition to be treated and the route of administration and will ultimately be at the discretion of the attendant physician. In guiding him in assessing the efficacy and acceptability of a regimen the physician may have recourse not only to changes in the recipient's gross condition but also to in vitro haematological procedures standard in the art, for example those specifically mentioned herein and also the erythrocyte filterability test described in the Dean and Schechter reference supra and in United States. Patent Specification No 4 137 309, Such an effective dose will generally be in the range 1 to 500 mg/kg bodyweight of human recipient per day, preferably in the range 5 to 100 mg/kg bodyweight per day and most preferably in the range 10 to 50 mg/kg bodyweight per day; an optimum dose is 20 mg/kg bodyweight per day. Unless otherwise indicated all weights are calculated as the carboxyl or 5-tetrazolyl acid of formula (I) : for compounds within the said formula wherein X is other than carboxyl or 5- tetrazolyl the figures would be amended proportionately. The desired dose is preferably presented as between two and four sub-doses administered at appropriate intervals throughout the day. Thus where three sub-doses are employed each will generally lie in the range 0.33 to 167, preferably 1.67 to 33.3 and most preferably 3.33 to 16.7 mg (acid)/kg bodyweight with an optimum of 6.67 mg (acid)/kg bodyweight. A daily dose for a human weighing of the order of 50 kg will thus generally lie in the range 50 mg. to 25g (acid), preferably in the range 250 mg. to 5g (acid) and most preferably in the range 500 mg to 2.5g (acid) and may be conveniently presented as three equal unit sub-doses of 16.7 mg to 8.33g (acid), preferably 83.3 mg to 1.67g (acid) and most preferably 167 mg to 833 mg (acid). Optimally a human daily dose is 1.0g (acid) conveniently presented as three unit sub-doses each of 333 mg (acid).

While it is possible for the compounds of formula (I) to be administered as the raw chemical it is preferable to present them as a pharmaceutical formulation preparation. The formulations of the present invention comprise a compound of formula (I), as above defined, together with one or more acceptable carriers therefor and optionally other therapeutic ingredients. The carrier(s) must be 'acceptable' in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The formulations include those suitable for oral, parenteral (including subcutaneous, intradermal, intramuscular and intravenous) and rectal administration although the most suitable route may depend upon for example the condition of the recipient. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. All methods include the step of bringing into association the compound of formula (I) (the active ingredient) with the carrier which constitutes one or more accessory ingredients. In general the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product into the desired formulation.

Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in- oil liquid emulsion. The active ingredient may also be presented as a bolus, electuary or paste.

A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free- flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, lubricating, surface active or dispersing agent. Moulded tablets may be_' made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein.

Formulations for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain antioxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze- dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.

Formulations for rectal administration may be presented as a suppository with the usual carriers such as cocoa butter.

Preferred unit dosage formulations are those containing a daily dose or unit daily sub-dose, as hereinabove recited, or an appropriate fraction thereof, of a compound of formula (I).

It should be understood that in addition to the ingredients particularly mentioned above the formulations of this invention may include other agents conventional in the art having regard to the type of formulation in question, for example those suitable for oral administration may include flavouring agents.

The compounds of formula (I) may also be presented as depot formulations of the kind known in the art from which the active ingredient is released, over a prolonged period, once the formulation is in place within the body of the recipient.

A further application for the compounds of formula (I) is the extracorpareal treatment of blood from the patient. As one possibility such treatment may be conducted in a batch-wise manner by removing an appropriate volume of blood, admixing it with the compound and transfusing the treated blood back into the patient. As an alternative possibility the treatment may be on a continuous basis, analogous to the well-known techniques for haemodialysis, whereby for a period of time blood is continously withdrawn, admixed with the compound and passed back into the patient. Both procedures should be conducted under sterile conditions and may be repeated as often as necessary: in either case the treatment may be monitored by means inter alia of the in vitro procedures previously mentioned. An effective blood concentration of f the compound of formula (I) will generall in the range 0.1 mM to 100 preferably in the range 0.3 mM to 33 mM and most preferably in the range 1 mM to 10 mM, with an optimum concentration of 3 mM.

The compounds of formula (I), as above defined, are also of value in the following further areas of human medicine.

(i) The palliation of pulmonary dysfunction, especially in emphysema or chronic bronchitis.

Pulmonary emphysema may be defined in pathological terms as an increase in the size of the air spaces distal to the terminal bronchioles, with destruction of their walls. In clinical practice the disease is associated also with chronic airflow obstruction.

Chronic bronchitis may be defined as chronic or recurrent cough with expectoration which cannot be attributed to conditions other than nonspecific lung disease.

(ii) Protection from the effects of hypoxia, for example the hypoxia encountered at high altitude.

(iii) The radiosensitization of tumours (i.e. the tumours are made more sensitive to radiation), as an adjunct to tumour radiotherapy.

For each of these further utilities the compounds of formula (I), as above defined, may be administered to the human recipient by the same routes, at the same doses and sub-doses and as the same pharmaceutical formulations as hereinabove described in respect of their use in the palliation of haemoglobinopathies, although it will be appreciated that the size of an effective dose will again depend upon the same general considerations as indicated hereinbefore, namely, the identity of the recipient, the condition involved and its severity and the route of administration, and that the most suitable route may depend for example upon the condition of the recipient. Where it is clinically desirable the compounds may also be used, in the same manner as hereinabove set forth, in the extracorporeal treatment of the patient's blood.

The compounds of formulae (II) to (XIII) as hereinbefore defined may be prepared by those methods known in the art for the synthesis of compounds of analogous structure : in particular, the compounds of formulae (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII) as hereinbefore defined may be prepared inter alia by methods analogous to those taught herein in respect of the compounds of formula (I) using appropriate starting materials and conditions as hereinbefore described.

It will be understood from the foregoing description that this invention may comprise any novel feature described herein, principally but not exclusively for example: <ul id="ul0008" list-style="none"><li>(a) Compounds of formula (I) as hereinbefore defined and salts thereof.</li><li>(b) Methods as hereinbefore described for the preparation of compounds according to (a) supra, together with the compounds when so prepared.</li><li>(c) Compounds of formula (I) as hereinbefore defined and pharmacologically acceptable salts thereof, for use in the medical treatment of a human being.</li><li>(d) Compounds of formula (I) as hereinbefore defined and pharmacologically acceptable salts thereof, for use in the palliation in a human being of a haemoglobinopathy.</li><li>(e) Compounds of formula (I) as hereinbefore defined and pharmacologically acceptable salts thereof, for use in the palliation in a human being of sickle-cell anaemia.</li><li>(f) A pharmaceutical formulation comprising a treatment-effective amount of a compound of formula (I) as hereinbefore defined or a pharmacologically acceptable salt thereof together with an acceptable carrier therefor.</li><li>(g) A method for the preparation of a formulation according to (f) surpa comprising admixture of the active ingredient, as defined, with the carrier therefor.</li><li>(h) A method for the palliation of a haemoglobinopathy comprising administering to a human being having such a condition a nor.- toxic, effective haemoglobinopathy-palliativc amount of a compound of formula (I) as hereinbefore defined or a pharmacologically acceptable salt thereof.</li><li>(i) A method according to (h) supra wherein the haemoglobinopathy is sickle-cell anaemia.</li><li>(j) Novel compounds of formulae (II) to (XIII) as hereinbefore defined, methods for their preparation as hereinbefore described and the compounds when so prepared.</li></ul>

The following Examples are provided in illustration of the present invention and should not be construed as in any way constituting a limitation thereof. All temperatures are in degrees Celsius.

Example 1

Proportion of 7- - 3- hydroxyphenoxy)heptanoic acid

(A) Ethyl 7- (2-formyl-3-methoxyphenoxy)heptanoate

2-Hydroxy-6-methoxybenzaldehyde (3.04 g, 0.02M), ethyl 7-bromo- heptanoate (4. 74 g, 0. 02M), anhydrous potassium carbonate (2. 97 g), sodium iodide (0.12 g) and ethanol (27 ml) were refluxed with stirring for 19 hr. The cooled reaction mixture was filtered and the solid washed with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether (40 ml) and water (40 ml). The organic layer was separated and washed with 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated to give ethyl 7- (2-formyl-3-methoxyphenoxy)heptanoate, 4. 2 g, 68% as an oil .

(B) 7-(2-Formyl-3-hydroxyphenoxy)heptanoic acid

To a stirred solution of ethyl 7- (2-formyl-3-methoxyphenoxy)heptanoate (4.15 g, 0. 0135M) in dry tetrahydrofuran (60 ml) was added dropwise a solution of magnesium iodide (5. 62 g, 0. 0202M) in dry ether (97. 5 ml). The mixture was then stirred under reflux (5 hr). The cooled mixuture was poured into 10% hydrochloric acid (65 ml). The organic layer was separated and the aqueous phase extracted with ethyl acetate. The combined organic solutions were washed with water and evaporated to dryness. The residue, ethyl 7- (2-formyl-3-hydroxyphenoxy)heptanoate, was dissolved in 2N sodium hydroxide solution (50 ml) with stirring at room temperature (10 hr). The solution was decanted from a residue and acidified with concentrated hydrochloric acid with cooling. The precipitated solid was filtered off and washed well with water to give 7- (2-formyl-3-hydroxyphenoxy)heptanoic acid, m. p. 106-107°C from benzene/petrol.

Example2

Preparation of 5-(2-formyl-3-hydroxy-4-n-propoxyphenoxy)pentanoic acid (A) 3-Methoxy-4-n-propoxyacetophenone

<img file="EP0054924A2_D0022.tif" />

with ether. The aqueous phase was acidified with concentrated hydrochloric acid and extracted with ether. The combined extracts were washed with water, dried (sodium sulphate) and evaporated. The product was then passed through a short pad of florisil eluting with chloroform-methanol (95:5) and the filtrate evaporated to give 3-methoxy-4-n-propoxyphenol as an oil which solidified on standing. After trituration with 40/60 petrol and filtration the product had m.p. 54-56° C.

(D) 3-Methoxy-4-n-propoxyphenol tetrahydropyranyl ether

3-Methoxy-4-n-propoxyphenol (19.62 g, 0.108M) was added in portions to a stirred mixture of dihydropyran (15.7 ml) and concentrated hydrochloric acid (3 drops) under nitrogen such that the temperature did not rise above 50° C. The solution was then stirred at room temperature (3 hr). The reaction mixture was diluted with ether and washed with water, 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated to give 3-methoxy-4-n-propoxyphenol tetrahydropyranyl ether.

(E) 6-Hydroxy-2-methoxy-3-n-propoxybenzaldehyde

1 ml of bromobenzene (11.88 ml) was added to a mixture of lithium chips (1.63 g) and anhydrous ether (90 ml) under nitrogen. When the reaction had commenced the remainder of the bromobenzene was added dropwise to the stirred mixture at such a rate as to cause gentle refluxing. After the addition was complete the mixture was stirred and refluxed (1 hr) and then cooled to room temperature. 3-Methoxy-4-n-propoxypheno1 tetrahydropyranyl ether (30.03 g, 0.113M) was added dropwise to the stirred mixture and then stirred at room temperature (3 days). A solution of anhydrous dimethyl formamide (8.5 ml) in anhydrous ether (8.5 ml) was added dropwise to the stirred mixture at such a rate as to cause gentle refluxing, and<img file="EP0054924A2_D0023.tif" />

G:: 5- (2-Formyl-3-hydroxy-4-n-propoxyphenoxy) pentanoicacid

2.5 ml of a solution cf iodine (6.64 g. 0.026M)in anhydrous ether (80 ml) was added to a stirredmixture ofmagnesiummetal (2.53 g. 0.105 g. <img file="EP0054924A2_D0024.tif" /> and ether (12.5 ml). When the reaction had commenced the remainder of the iodine solution was added dropwise at such a rate as to cause gentle refluxing. Afterthe addition was complete the reaction mixture was heated to reflux until a colourless solution was obtained (15 mins). The cooled reaction mixture was filtered and the unreacted magnesium metal was washed with ether. The colourless solution of magnesium iodide thus obtained was added dropwise to a stirred solution of ethyl 5-(2-formyl-3-methoxy-4-n-propoxyphenoxy)pentanoate (5.95 g, 0.0176M) in anhydrous tetrahydrofuran (50 ml). The mixture was brought to reflux with stirring for 5.5 hr. The cooled reaction mixture was poured into 2N hydrochloric acid (75 ml). The organic layer was separated and the aqueous layer was extracted with ethyl acetate. The combined extracts were washed with water, dried (sodium sulphate) and evaporated. The residue was dissolved in 95% ethanol (50 ml), 2N sodium hydroxide solution (50 ml) added and the mixture stirred at room temperature (4 hr). After evaporation of the ethanol the residue was diluted with water, washed with ether and acidified with concentrated hydrochloric acid. The oily product was extracted with ether, the combined extracts washed with water and extracted with 5% sodium bicarbonate solution. The combined extracts were acidified with concentrated hydrochloric acid to pH3 with ice cooling, and the gummy solid produced was filtered off and washed with water. This was chromatographed on kieselgel G (200 g) eluting with chloroform-methanol (9:1), the combined fractions evaporated and the residue recrystallised from _benzene-petrol to give 5-(2-formyl-3-hydroxy-4-n-propoxyphenoxy)pentanoic acid, m.p. 78-79⁰ C. (Found: C, 60.65; H, 6.96. C₁₅H₂₀0₆ requires C, 60.80; H, 6.80%).

Example 3

Preparation of 5-(4,6-dichloro-2-formyl-3-hydroxyphenoxy)pentanoic acid

(A) Ethyl 5-(2-formyl-3-benzyloxyphenoxy)pentanoate

A mixture of 2-hydroxy-6-benzyloxybenzalde- hyde (3.0 g, 0.013M), ethyl 5-bromopentanoate (2.75 g, 0.013M), anhydrous potassium carbonate (2.16 g, 0.0156M), sodium iodide (0.195 g) and dry dimethylformamide (15 ml) were stirred at 60-80°C for 3 hours and then left to stir at room temperature overnight. The mixture was then poured into water (50 ml) and the product extracted with ether (2 x 80 ml) and the combined extracts washed with 10% aqueous sodium hydroxide (2 x 20 ml) and then with water to neutrality, dried, and evaporated to give ethyl 5-(2-formyl-3-benzyloxy- phenoxy)pentanoate, (4.D g, 86%) as a pale yellow oil.

(B) 5-(2-Formyl-3-benzyloxyphenoxy)pentanoic acid

A mixture of ethyl 5-(2-formyl-3-benzyloxy- phenoxy)pentanoate (3.61 g, 0.01M), potassium hydroxide (1.19 g, 0.021M) and ethanol (40 ml) were stirred at 50-60°C for 5 hours. The ethanol was then removed in vacuo, the residue dissolved in water (50 ml) and the solution extracted with ether (2 x 80 ml). The aqueous layer was then<img file="EP0054924A2_D0025.tif" /> and evaporated. The residue was chromatographed on kieselgel G (50 g) eluting with chloroform-methanol (95:5). The combined fractions were evaporated and the residue recrystallised from benzene-petrol to give 5-(4,6-dichloro-2,formyl-3-hydroxyphenoxy)pentanoic acid, m.p. 85-87° C. (Found: C, 46.69; H, 3.92. C₁₂H₁₂C₁₂0₅ requires C, 46.92; H, 3.94%).

Example 4

Preparation of 5-(2-formyl-3-hydroxyphenoxy)-N-methylsulphonylpentanamide

(A) 5-(4-Benzofuranyloxy)pentanoic acid

4-Hydroxybenzofuran (4.9g,0.0366M), ethyl 5-bromopentanoate (7.64 g, 0.0366M), anhydrous potassium carbonate (5.44 g), sodium iodide (0.2 g) and 95% ethanol (20 ml) were refluxed with stirring for 4.5 hr. The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The organic layer was separated and washed with 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated to give ethyl 5-(4-benzofuranyloxy)pentanoate as an oil. To this oil was added 95% ethanol (130 ml) and 0.5N sodium hydroxide solution (130 ml) and the mixture stirred at room temperature (3 hr). The solution was evaporated to half-volume, diluted with water and extracted with ether. The aqueous phase was treated with charcoal, filtered and acidified with concentrated hydrochloric acid. The precipitated solid was filtered off, washed well with water and recrystallised from ethanol-water to give 5-(4-benzofuranyloxy)pentanoic acid, m.p. 107.5-108.5° C. (Found: C, 66.51; ^{H, 5.90. C}₁₃^H₁₄⁰₄ requires C, 66.65; H, 6.02%).<img file="EP0054924A2_D0026.tif" /> the solution (5 mins) to remove excess ozone before the addition of dimethyl sulphide (0.9 ml). The mixture was allowed to warm to room temperature overnight (16 hr). The solvent was removed in vacuo, the residue dissolved in ethyl acetate-ether (1:1), washed with water and extracted with 5% sodium bicarbonate solution. The combined extracts were acidified with concentrated hydrochloric acid and the precipitated solid was filtered off, washed well with water and recrystallised from ethyl acetate-petrol to give 5-(2-formyl-3-hydroxyphenoxy)-N-methylsulphonyl- pentanamide, m.p. 136-138° C. (Found: C, 49.54; H, 5.33; N, 4.12; S, 10.14. C₁₃H₁₇NSO₆ requires C, 49.51; H, 5.43; N, 4.44; S, 10.17%).

Example 5

Preparation of ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate (A) Ethyl 4-(4-benzofuranyloxymethyl)benzoate

4-Hydroxybenzofuran (1.34 g, 0.01M), ethyl 4-bromomethylbenzoate (2.43 g, 0.01M), anhydrous potassium carbonate (1.49 g), sodium iodide (0.06 g) and 95% ethanol (10 ml) were refluxed with stirring (5 hr). The cooled reaction mixture was diluted with 0.5N sodium hydroxide solution and cooled in ice. The precipitated solid was filtered off, washed well with water and recrystallised form ethanol-water to give ethyl 4-(4-benzofuranyloxymethyl) benzoate, m.p. 70-72° C. (Found: C, 72.79; H, 5.46. C₁₈H₁₆0₄ requires C, 72.96; H, 5.44%).

(B) Ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate

Ethyl 4-(4-benzofuranyloxymethy1)benzoate (1.184 g, 0.004M) was dissolved in absolute ethanol (180 ml) and cooled to -65° C with stirring and exclusion of moisture. Ozonised air was bubbled through the solution at a rate of 20 litres/hr for 1 hr. Nitrogen was then bubbled through the solution (5 mins) to remove excess ozone before the addition of dimethyl sulphide (1.2 ml). The mixture was allowed to warm to room temperature overnight (16 hr). The solvent was removed in vacuo and the residue recrystallised from ethyl acetate-petrol to give ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate, m.p. 105-107^c C. (Found: C, 67.59; H, 5.21. C₁₇H₁₆O₅ requires C, 67.99; H, 5.37%).

Example 6

Preparation of 4-(2-formyl-3-hydroxyphenoxymethyl)benzoic acid

Ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate (0.6 g, 0.002M)was suspendedin 95% ethanol (5 ml) and IN sodium hydroxide solution (5 ml) and stirred at room temperature (2.5 hr). The yellow solution was diluted with water, extracted with ethyl acetate, and acidified with concentrated hydrochloric acid. The precipitated solid was filtered off, washed well with water, and recrystallised from 95% ethanol to give 4-(2-formyl-3-hydroxyphenoxymethyl) benzoic acid, m.p. 239-240° C. (Found: C, 65.99; 4.29. C₁₅H₁₂O₅ requires C, 66.17; H. 4.44%).

Example 7

Preparation of (4-chloro-2-formyl-3-hydroxyphenoxy)pentanoic acid

(A) 4-Chloro-3-methoxyphenol methoxymethyl ether .

4-Chloro-3-methoxyphenol (4.755 g, 0.03M), dimethoxymethane (10.26 g, 0.135M, toluene-4-sulphonic acid (120 mg) and dry dichloromethane (180 ml) were refluxed under nitrogen and a soxhlet containing molecular sieve (type 3A, previously dried at 120° C) for 48 hr. After 24 hr a further 60 mg of toluene-4-sulphonic acid was added. On cooling, triethylamine (0.6 ml) was added and the solution washed with 1N sodium hydroxide solution, water, dried (sodium sulphate) evaporated and the residue distilled in vacuo to give 4-chloro-3-methoxyphenol methoxymethyl ether, b.p. 83-86° C/0.3 mmHg.

(B) 3-Chloro-6-hydroxy-2-methoxybenzaldehyde

4-Chloro-3-methoxyphenol methoxymethyl ether (3.1 g, 0.0153M) in dry ether (3.5 ml) was added dropwise to a solution of phenyllithium (from 0.21 g lithium and 2.4 g bromobenzene) in dry ether (12 ml) under nitrogen and the mixture stirred at room temperature (3 days). A solution of dry dimethylformamide (1.12 g, 0.0153M) in dry ether (1 ml) was then added dropwise over 15 mins and the mixture stirred at room temparature (1 hr). The reaction mixture was poured into 2N sulphuric acid (100 ml) and extracted with ethyl acetate. The combined extracts were dried (sodium sulphate) and evaporated. The_-residue was dissolved in methanol (25 ml), 3N hydrochloric acid ( 10ml) added and the resultant solution stirred at 65° C for 30 mins. The solvent was removed in vacuo and the residue diluted with water (50 ml) and extracted with ether. The combined extracts were dried (sodium sulphate) and evaporated. The residue was chromatographed on silica (MFC) eluting with chloroform. The fractions were combined and evaporated to give 3-chloro-6-hydroxy-2-methoxybenzaldehyde as an oil which crystallised on standing. (Found: m/e 186.0084. C₈H₇CIO₃ requires M186.0082).

(C) Ethyl 5-(4-chloro-2-formyl-3-methoxyphenoxy)pentanoate

- 3-Chloro-6-hydroxy-2-methoxybenzaldehyde (1.9 g, 0.0102M), ethyl 5-bromopentanoate (2.13 g, 0.0102M), anhydrous potassium carbonate (1.55 g), sodium iodide (56 mg), and 95% ethanol (25 ml) were refluxed with stirring (17 hr). The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The organic layer are separated and washed with 2N sodium hydroxide solution, water, dried (magnesium sulphate) and evaporated to give ethyl 5-(4-chloro-2-formyl-3-methoxyphenoxy)pentanoate as an oil.

(D) 5-(4-Chloro-2-formyl-3-hydroxyphenoxy)pentanoic acid

To a solution of ethyl 5-(4-chloro-2-formyl-3-methoxyphenoxy)pentanoate (2.0 g, 0.00636M) in anhydrous tetrahydrofuran (30 ml) was added dropwise a solution of magnesium iodide (1.737 g, 0.00965M) in anhydrous ether (50 ml). The mixture was then refluxed with stirring for 5 hr. The cooled reaction mixture was poured into 10% hydrochloric acid (30 ml). The organic layer was separated and the aqueous phase extracted with ethyl acetate. The combined organic phases were evaporated to dryness and the residue dissolved <img file="EP0054924A2_D0027.tif" />precipitated solid was filtered off, washed well with water and recrystallised from ethyl acetate-petrol to give 5-(4-chloro-2-formyl-3-hydroxyphenoxy) pentanoic acid, m.p. 123-124° C. (Found: C, 52.97; H, 4.69; Cl, 12.98. C₁₂H₁₃C10₅ requires C, 52. 84 ; H, 4.77 ; Cl, 13.03%).

Example 8

Preparation of 5-(3-acetylamino-2-formylphenoxy)pentanoic acid

2-Acetylamino-6-hydroxybenzaldehyde (0.895 g, 0.005M), ethyl 5-bromopentanoate (1.05 g, 0.005M), anhydrous potassium carbonate (0.76 g), sodium iodide (50 mg) and 95% ethanol (20 ml) were refluxed with stirring for 16 hr. The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The organic layer was separated and washed with 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated. The residue (ethyl 5-(3-acetylamino-2-formylphenoxy)-pentanoate) was dissolved in 95% ethanol (20 ml) and treated with stirring over 1 hour with 1N sodium hydroxide (4.5 ml), and then stirred at room temperature (2 hours). The solution was evaporated to one-third volume, diluted with water (10 ml) and acidified with concentrated hydrochloric acid with cooling. The precipitated solid was filtered off, washed well with water and recrystallised from benzene/petrol (charcoal) to give 5-(3-acetylamino-2-formylphenoxy)pentanoic acid, m.p. 119-121°C. (Found: C, 60.55; H, 6.26; N, 4.88%. C₁₄H_l7NO₅ requires C, 60.22; H, 6.09; N, 5.02%).

Example 9

Preparation of 4-(2-formyl-3-hydroxyphenoxy)butanoic acid

(A) 4-(4-Benzofuranyloxy)butanoic acid

4-Hydroxybenzofuran (1.0 g., 0.00746M), ethyl 4-bromobutanoate (1.46 g, 0.00746M), anhydrous potassium carbonate (1.13 g), sodium iodide (50 mg) and 95% ethanol (20 ml) were reacted together to give ethyl 4-(4-benzo- furanyloxy)butanoate which was subsequently hydrolysed, as previously described for the preparation of 5-(4-benzofuranyloxy)pentanoic acid, to give 4-(4-benzofuranyloxy)butanoic acid, m.p. 91-93°C. (Found: C, 65.50; H, 5.40. C₁₂H₁₂0₄ requires C, 65.45; H, 5.45%).

(B) 4-(2-Fomyl-3-hydroxyphenoxy)butanoic acid

4-(4-Benzofuranyloxy)butanoic acid (0.66 g, 0.003M) was dissolved in dry methanol (135 ml), cooled to -65°C with stirring and ozonised as previously described for the preparation of 5-(2-formyl-3-hydroxyphenoxy) -N-methylsulphonylpentanamide, to give 4-(2-formyl-3-hydroxyphenoxy)butanoic acid, m.p. 151-153°C. (Found: C, 58.70; H, 5.39. C₁₁H₁₂O₅ requires C, 58.93; H, 5.36%).

Example 10

Preparation of 6-(2-formyl-3-hydroxyphenoxy)hexanoic acid

(A) 6-(4-Benzofuranyloxy)hexanoic acid

4-Hydroxybenzofuran (1.3 g, 0.0097M), ethyl 6-bromohexanoate (2.17 g, 0.0097M), anhydrous potassium carbonate (1.44 g), sodium iodide (60 mg) and 95% ethanol (10 ml) were reacted together to give ethyl 6-(4-benzofuranyloxy)-<img file="EP0054924A2_D0028.tif" />

(B) 5-(2-Formyl-3-hydroxyphenoxy)hexanoic acid

6-(4-Benzofuranyloxy)hexanoic acid (0.496 g, 0.002M) was dissolved in dry methanol (75 ml), cooled to -65°C with stirring and ozonised as previously described for the preparation of 5-(2-formyl-3-hydroxyphenoxy)-N-methylsulphonylpentanamide, to give 6-(2-formyl-3-hydroxyphenoxy)hexanoic acid, m.p. 90-92⁰C (benzene-petrol). (Found: C, 61.88; H, 6.29. C₁₃H₁₆O₅ requires C, 61.89; H, 6.39%).

Example 11

Preparation of ethyl 4-(3-acetylamino-2-formylphenoxymethyl)benzoate

2-Acetylamino-6-hydroxybenzaldehyde (0.45 g, 0.0025M), ethyl 4-bromomethylbenzoate (0.61 g, 0.0025M), anhydrous potassium carbonate (0.38 g), sodium iodide (50 mg) and 95% ethanol (20 ml) were reacted together (4<maths id="math0001" num=""><img file="EP0054924A2_D0029.tif" /></maths> hr) _____ to give ethyl 4-(3-acetylamino-2-formylphenoxy- methy1)benzoate, m.p. 116-119°C (ethanol). (Found: C, 66.76; H, 5.61; N, 3.87%. C₁₉H₁₉NO₅ requires C, 66.85; H, 5.61; N, 4.10%).

Example 12

Preparation of 4-(3-acetylamino-2-formylphenoxymethyl)benzoic acid -

Ethyl 4-(3-acetylamino-2-formylphenoxymethyl)benzoate (0.45 g, 0.00132M) was suspended in 95% ethanol (10 ml) with stirring and treated with 1N sodium hydroxide solution (1.32 ml) over 1 hour. The mixture was then diluted with water (3 ml) and stirred at room temperature overnight. A further 15 ml of water was added and the mixture stirred at room temperature (4 hr). The mixture was then extracted with ethyl acetate and the aqueous phase acidified with concentrated hydrochloric acid with cooling. The precipitated solid was filtered off, washed well with water, and recrystallised from ethanol to give 4-(3-acetylamino-2-formylphenoxymethyl)-benzoic acid, m.p. 242-244⁰ C (dec.) (Found: C, 65.27; H, 4.93; N, 4.23%. C₁₇H₁₅NO₅ requires C, 65.17; H, 4.83; N, 4.47%).

Example 13

2-(2-Formyl-3-hydroxyphenoxymethyl) benzoic acid

(A) Methyl 2-(2-methyl-4-benzofuranyloxymethyl)benzoate

4-Hydroxy-2-methylbenzofuran (2.13g, 14.4mM), methyl 2-bromomethylbenzoate (3.29g, 14.4mM), anhydrous potassium carbonate (2.135g), sodium iodide (87mg) and methanol (20ml) were reacted together in an analogous manner to that described in example 5(A) to give methyl 2-(2-methyl-4-benzofuranyloxymethyl)benzoate, m.p. 93-95 C. (Found: C,72.74; H,5.26. C₁₈H₁₆0₄ requires C,72.96; H,5.44%).

(B) 2-(2-Formyl-3-hydroxyphenoxymethyl)benzoic acid

A mixture of methyl and ethyl 2-(2-methyl-4-benzofuranyloxymethyl) benzoates (1.212g) was dissolved in absolute ethanol (180ml) and ozonised in an analogous manner to that described in example 5(B) to give a mixture of methyl and ethyl esters of 2-(3-acetoxy-2-formylphenoxy- methyl)benzoic acid, as an oil. This oil was dissolved in 95% ethanol (15ml) and treated with 1N sodium hydroxide solution (15ml) in an analogous marker to that described in example 6 to give 2-(2-formyl-3-hydroxyphenoxy- methyl)benzoic acid, m.p. 218-219.5°C. (Found: C,65.91; H,4.50. ^C₁₅^H₁₂⁰₅<img file="EP0054924A2_D0030.tif" /> C,66.17; H,4.44%).

Example 14

5-[4-(2-Formyl-3-hydroxyphenoxymethyl)phenyl] tetrazole

(A) 4-(2-Methyl-4-benzofuran

y

loxymethyl)benzonitrile

4-Hydroxy-2-methylbenzofuran (5.18g, 0.035M), 4-bromemethylbenzonitrile (6.86g, 0.035M), anhydrous potassium carbonate (5.2g), sodium iodide (0.21g) and 95% ethanol (50ml) were reacted together in an analogous manner to that described in example 5(A) to give 4-(2-methyl-4-benzo- furanyloxymethyl benzonitrile, m.p. 84-85°C. (Found: C,77.57; H,5.02; N,5.22. C₁₇H₁₃ NO₂ requires C,7.55; H.4.98; N,5.32.

(B) 5-[4-(2-methyl-4-benzofuranyloxymethyl)phenyl]tetrazole

4-(2-Methyl-4-benzofuranyloxymethyl)benzonitrile (3.92g, 0.015M), sodium azide (0.97g), ammonium chloride (0.8g) and dimethylformamide (20ml) were stirred and heated at 125-130°C for 3 hours. The mixture was cooled slightly and poured into a mixture of 2N sodium hydroxide, ice, and sodium nitrite (0.065g). This mixture was extracted with ether and the aqueous phase acidified with conc. hydrochloric acid. The resulting solid was filtered off, washed with water, dried, and recrystallised from ethyl acetate/petrol to give 5-[4-(2-methyl-4-benzofuranyloxymethyl)phenyl] tetrazole, m.p. 196-197 C. (Found: C,66.79 ; H,4.53 ; N,18.28. C_l7H₁₄N₄O₂ requires C,66.65; H,4.61; N,18.29%).

(C) 5-[4-(2-Formyl-3-hydroxyphenoxymethyl)phenyl]tetrazole

5-[4-(2-Methyl-4-benzofuranyloxymethyl)phenyl]tetrazole (1.224g, 0.004M) was dissolved in a mixture of dry methanol (130ml) and dry dimethylformamide (20ml), and cooled to -65⁰C with stirring and exclusion of moisture. Ozonised air was bubbled through the solution at a rate of 20 litres/hr for lhr. Nitrogen was then bubbled through the solution (5 mins) to remove excess ozone before the addition of dimethyl sulphide (1.2ml). The mixture was allowed to warm to room temperature overnight (16hr). The solvent was removed in vacuo and the residual oil dissolved in ethyl acetate and washed with 2N hydrochloric acid, water, and extracted with sodium bicarbonate solution. The combined extracts were acidified with 2N hydrochloric acid to give a solid which was filtered off and dried. This mixture of 5-[4-(2-formyl-3-hydroxyphenoxymethyl)phenyl]tetrazole and 5-[4-(3-acetoxy- 2-formylphenoxymetyl)phenyl]tetrazole was suspended, in 95% ethano.l (20ml) and IN sodium hydroxide (20ml) and stirred at room temperature (1.5hr). The solution was evaporated and the residue diluted with water and acidified. The resulting solid was filtered off, washed with water, dried, and recrystallised from ethanol/water to give 5-[4-(2-formyl-3-hydroxyphenoxy- methyl)phenyl]tetrazole as the 0.5 hydrate, m.p. 206-206.5°C (Found: C,59.00; H,4.29; N,18.46. C₁₅H₁₂N₄O₃O 0.5H₂O requires C,59.01; H,4.29; N,18.35%).

Example 15

5-(2-Formyl-3-hydroxy-4-methoxyphenoxy)pentanoic acid

(A) 3,4-Dimethoxyphenol tetrahydropyranyl ether

3,4-Dimethoxyphenol (30.8g) was added in small portions to a mixture of dihydropyran (29.2ml) and cone. hydrochloric acid (3 drops) under nitrogen so that the temperature did not rise above 50⁰C. After the addition was complete the dark solution was stirred at room temperature for 3 hrs, and then diluted with ether. The resulting solution was washed with water, 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated to give 3,4-dimethoxyphenol tetrahydropyranyl ether.

(B) 2,3-Dimethoxy-6-hYdroxybenzaldehyde

3,4-Dimethoxyphenol tetrahydropyranyl ether (47.6g, 0.2M) was lithiated with phenyllithium (from 21.02ml bromobenzene and 2.89g lithium), formylated by the addition of dry dimethylformamide (15ml) and subsequently hydrolysed in an analogous manner to that described in example 2(E). The crude product was distilled under high vacuum to give 2,3-dimethoxy-6-hydroxybenzaldehyde as a yellow oil which solidified on standing. After trituration with 40/60 petrol and filtration the product had m.p. 53-54°C. (Found: C,59.18; H,5.54. C₉H₁₀0₄ requires C,59.33; H,5.53%).

(C) 5-(2-Formyl-3-hydroxy-4-methoxyphenoxy)pentanoic acid

2,3-Dimethoxy-6-hydroxybenzaldehyde (5.46g, 0.03M), ethyl 5-bromopentanoate (6.273g, 0.03M), anhydrous potassium carbonate (4.45g), sodium iodide (0.185g) and 95% ethanol (25ml) were reacted together in an analogous manner to that described in example 2(F).to give ethyl 5-(2-formyl-3,4-dimethoxyphenoxy)pentanoate as an oil. This ester was demethylated with magnesium iodide (from 7.18g iodine) in an analogous manner to that described in example 2(G), except that the ethyl acetate solution obtained on work-up of the demethylation was extracted with 2N sodium hydroxide solution. The combined extracts were acidified with conc. hydrochloric acid and the oily product extracted into ether. The combined extracts were washed with water, extracted with sodium bicarbonate solution and the combined extracts acidified to give a solid which was filtered off, washed with water and dried. This product was passed through a column of kieselgel eluting with chloroform-methanol (95:5) and the p rified product was recrystallised from benzene, m.p. 105-107°C. (Found: C,58.43; H,5.9^{6. C}₁₃^H₁₆⁰₂ requires C,58.20; H,6.01%).

Example 16

3-(2-Formyl-3-hydroxy

p

henoxy)propionitrile

(A) 3-(4-Benzofuranyloxy)propionitrile

4-Hydroxybenzofuran (2.68g, 0.02M), acrylonitrile (5.4ml), and Triton B (0.2ml) were refluxed on a steam-bath for 48 hrs. The cooled mixture was diluted with ether/ethyl acetate (1:3) (100ml) and the solution washed with 1.5N sodium hydroxide solution, 1N hydrochloric acid, water, dried (sodium sulphate) and evaporated to give 3-(4-benzofuranyloxy) propionitrile as a colourless oil which solidified in the refrigerator. (Found: M⁺ I87.0633. C₁₁H₉N0₂ requires 187.0633).

(B) 3-(2-Formyl-3-hydroxyphenoxy)propionitrile

3-(4-Benzofuranyloxy)propionitrile (0.935g,5 mM) was dissolved in absolute ethanol (225ml) and ozonised in an analogous manner to that described in example 5(B) to give 3-(2-formyl-3-hydroxyphenoxy)propionitrile which was recrystallised from ethyl acetate/petrol, m.p. 84-86°C. (Found: C,62.56; H,4.79; N,6.99. C₁₀H₉NO₃ requires C,62.83; H,4.71; N,7.33%).

Example 17

4-(2-Formyl-3-hydroxyphenoxymethyl)benzoic acid

(A) Ethyl 4-(2-methyl-4-benzofuranyloxymethyl)benzoate

4-Hydroxy-2-methylbenzofuran (7.4g, 0.05M), ethyl 4-bromomethylbenzoate (12.15g, 0.05M), anhydrous potassium carbonate (7.59g), sodium iodide (0.5g), and 95% ethanol were reacted together in an analogous manner to that described in example 5(A) to give ethyl 4-(2-methyl-4-benzofuranyloxy- methyl)benzoate which was recrystallised from ethanol/water, m.p. 59-61°C. (Found: C,73.73; H,6.03. C₁₉H₁₈0₄ requires C,73.55; H,5.81%).

(B) Ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate

To a stirred solution of the product of step (A) (lOg) in glacial acetic acid (200ml) at 60-70 C was added a solution of sodium dichromate dihydrate (22.5g) in water (50ml), over 10 minutes. The reaction mixture was maintained at 70°C for 1 hour and then diluted with water (lL). The cloudy suspension was extracted with ethyl acetate (3 x 300m1) and the combined extracts washed with water (3 x 200ml) and brine (300ml). After drying (magnesium sulphate) the solution was filtered through florisil (1 cm pad) and evaporated to yield a red solid (9.8g). This was dissolved in chloroform and passed down a florisil column (50g, ~ abem long) eluting with chloroform. The yellow fraction was collected and evaporated to give a yellow solid.

(C) 4-(2-Formyl-3-hydroxyphenoxymethyl)benzoic acid

The product from step (B) (7.9g) was suspended in methanol (90ml) and stirred with 1N sodium hydroxide solution (90ml) for 2.5 hours. The resulting dark solution was evaporated to half volume and then diluted with water (160ml) and acidified with concentrated hydrochloric acid, with cooling in an ice bath. The precipitated product was collected by filtration, washed with water (200ml), sucked dry and recrystallised from aqueous dimethylformamide. The title compound was isolated as yellow crystals after drying in vacuo at 60^oC, m.p. 240-242^oC. (sinters at ~ 225°C)

Example 18

4-(2-Formyl-3-hydroxyphenoxymethyl)benzoic acid

(A) 4-Methoxymethoxy-2-methylbenzofuran

To a stirred mixture of 4-hydroxy-2-methyl benzofuran (7.1g, 0.048M), anhydrous powdered potassium carbonate (19.87g) and acetone (82ml), was added dropwise bromomethoxymethane (11.99g, 7.88ml, 0.0959M) with ice cooling. After the addition was complete the reaction mixture was stirred at room temperature overnight, filtered and evaporated. The residual oil was distilled to give 4-methoxymethoxy-2-methylbenzofuran, b.p. 94-97°C/ 0.8mmHg.

(B) 2-Hydroxy-6-methoxymethoxybenzaldehyde

4-Methoxymethoxy-2-methylbenzofuran (6.7g, 0.0349M) was dissolved in dry methanol (800ml) and ozonised in an analogous manner to that described in example 5(B). After evaporation of solvent the residual oil (2-acetoxy-6-methoxymethoxybenzaldehyde dimethyl acetal) was dissolved in methanol (100ml) and treated with 1N sodium hydroxide solution (72ml) with stirring at room temperature (2hrs). The solution was evaporated to one-third volume, the residue diluted with water (100ml) and acidified to pH5 with citric acid. The liberated oil extracted into ether, and the combined was extracts evaporated. The residual oil (2-hydroxy-6-methoxy- methoxybenzaldehyde dimethyl acetal) was dissolved in tetrahydrofuran (80ml) and the solution treated with 5% citric acid solution (80ml) with stirring at room temperature (2hrs). The solution was evaporated to half-volume and diluted with water (80ml). The mixture was extracted with ether and the combined extracts extracted with 1N sodium hydroxide solution. The combined extracts were immediately acidified to pH5 with solid citric acid, and the liberated oil extracted into ether. The combined extracts were washed with 5% sodium bicarbonate solution, water, dried (sodium sulphate) and evaporated to give 2-hydroxy-6-methoxymethoxy- benzaldehyde as an oil which solidified on standing, m.p. 47-49°C.

(C) Ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate

To a stirred solution of 2-hydroxy-6-methoxymethoxybenzaldehyde (0.91g, 5.lmM) in dry dimethyl sulphoxide (8ml) was added potassium t-butoxide (0.57g, 51mM) with exclusion of moisture. After 10mins. ethyl 4-bromomethylbenzoate (1.22g, 5mM) was added and the whole stirred at room temperature (18hrs). The reaction mixture was poured into water (100ml) and the liberated oil extracted into ether. The combined extracts were washed with 5% sodium carbonate solution, water, dried (sodium sulphate) and evaporated. The residual oil (ethyl 4-(2-formyl-3-methoxymethoxy-phenoxymethyl)benzoate) was dissolved in ethanol (30ml) and treated with 3N hydrochloric acid (30ml) with stirring at 60⁰C (30mins). The solid was filtered off, washed with water, dried, and recrystallised from ethanol/water to give ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)-benzoate, m.p. 105-107°C (identical to a sample previously prepared, example 5(B).

(D) 4-(2-Formyl-3-hydroxyphenoxymethyl)benzoic acid

Ethyl 4-(2-formyl-3-hydroxyphenoxymethyl)benzoate was hydrolysed as previously described (example 6) to give 4-(2-formyl-3-hydroxyphenor methyl)benzoic acid, m.p. 239-240°C.

Example 19

Anti-sickling potency in vitro

In an aerated sample of whole homozygous human sickle cell blood, i.e. one maintained at an oxygen tension of 150 mm. Hg, the proportion of normal discoid erythrocytes is usually greater than 90%. If the oxygen tension is reduced the proportion of normal cells decreases because there is an inverse increase in the proportion of sickle and bizarre cells and at an oxygen tension of 28 mm. Hg the proportion of normal cells lies in the range 45-65%. In the presence of an effective concentration of an anti-sickling agent the proportion of normal cells at such low oxygen tensions is increased.

A suitable index of the in vitro anti-sickling potency (ASP) of a compound in whole homozygous human sickle cell blood may be calculated from the equation<maths id="math0002" num=""><img file="EP0054924A2_D0031.tif" /></maths>wherein <ul id="ul0009" list-style="none"><li>"control" refers to blood samples maintained under a reduced oxygen tension (28 mm. Hg);</li><li>"test" refers to blood samples maintained at 28 mm. Hg as for "control" samples but containing a known concentration of test compound;</li><li>"aerated" refers to blood samples maintained at high oxygen tension (150 mm. Hg); and</li><li>the percentages refer to the proportion of normal discoid erythrocytes.</li></ul>

The potencies for a number of compounds are presented in the following table. A figure of less than 20 indicates that the compound is essentially inactive (at the test concentration) in this procedure while a negative number denotes an increase in sickling in the presence of the compound. <tables id="tabl0001" num="0001"><img file="EP0054924A2_D0032.tif" /></tables><ul id="ul0010" list-style="none"><li>(A) : Potassium cyanate (see inter alia the Dean and Schechter reference supra)</li><li>(B) : 3,4-Dihydro-2,2-dimethyl-2H-1 benzopyran-6-butyric acid (Nature, 258, December 25, 1975, 743-746)</li><li>(C) : Methylenebisphosphonic acid (U.S. Patent 4 137 309)</li></ul>

Example 20

Effect on the oxygen-dissociation curve of whole normal human blood in vitro

The compounds under investigation were separately added to aliquots of heparinised normal (AA genotype) adult human whole blood. Each sample was incubated (30 mins., 37 C.) and the oxygen-dissociation curve then determined using a whole-blood spectrophotometer (Hem-0-Scan, Trade Name).

Figure 1 shows the concentration-dependent left displacement of the dissociation curve seen with 4-(2-formyl-3-hydroxyphenoxymethyl) benzoic acid, the indicated concentrations being with respect to the whole-blood volume.

Example 21

Toxicity Data

The acute oral LD₅₀ in mice of 4-(2-formyl-3-hydroxyphenoxymethyl) benzoic acid, administered as a solution in sodium bicarbonate-saline, was found to be approximately 400 mg/kg.

The acute oral LD₅₀ in rats of 4-(2-formyl-3-hydroxy- phenoxymethyl) benzoic acid, administered as a solution in sodium bicarbonate-saline, was found to be in excess of lg./kg.

Example 22

<tables id="tabl0002" num="0002"><img file="EP0054924A2_D0033.tif" /></tables>The Compound, Lactose and Starch are mixed together and then granulated with a solution of Polyvinylpyrrolidone in water. After drying the granules, the Magnesium Stearate is mixed in and tablets compressed at an average weight of 460 mg.

(B) CAPSULE

<tables id="tabl0003" num="0003"><img file="EP0054924A2_D0034.tif" /></tables>The Compound, Dibasic Calcium Phosphate, Dihydrate and Sodium Starch Glycolate are mixed together and then granulated with a solution of the Methylcellulose in water. After drying, the granules are mixed with the Stearic Acid and Talc and the mixture filled into gelatin capsules at an average fill weight of 430 mg.

(C) SUPPOSITORY

<tables id="tabl0004" num="0004"><img file="EP0054924A2_D0035.tif" /></tables>Grind the Compound to a particle size below 150µ. Add the suppository base at 38-40°C. Mix to give a uniform dispersion. Pour into suppository moulds and allow to cool.

(D) INJECTION - Single dose, intravenous

<tables id="tabl0005" num="0005"><img file="EP0054924A2_D0036.tif" /></tables>Suspend the Compound in some of the Water for Injections. Adjust the pH to 10 to 10.5 by addition of Sodium Hydroxide Solution. Add sufficient Water for Injections to produce the required final volume. Re-check the pH. Sterilise by passage through a sterile membrane filter of 0.22p pore size. Fill under aseptic conditions into sterile vials and freeze dry.

(E) INJECTION - Multidose, intramuscular

<tables id="tabl0006" num="0006"><img file="EP0054924A2_D0037.tif" /></tables>Dissolve the Polysorbate 20, Polyvinylpyirolidone, Sodium Chloride and Chlorocresol in Water for Injections. Sterile filter, 0.22µ. Grind the sterile Compound to a particle size below 20p and add to the filtered solution. Mix until a uniform dispersion is achieved. Fill into sterile glass vials.

(F) PROLONGED RELEASE TABLET

<tables id="tabl0007" num="0007"><img file="EP0054924A2_D0038.tif" /></tables>Melt the Hydrogenated Castor Oil and add the Compound, ground to a particle size of less than 150µ. Add the Casein. Mix until uniform. Allow to cool and mill to a granule. Mix in the Magnesium Stearate and compress to an average weight of 1,200 mg.

In the foregoing the "Compound" refers to a compound of formula (I) as hereinbefore defined, the weight thereof being calculated as the appropriate carboxyl or 5-tetrazolyl acid as hereinbefore described.