Epimeric azahomoerythromycin a derivative and intermediates therefor

(74) Attorney Cand. Johan H. Gerbitz,

Bryn & Aarflot A / S, Oslo.

(30) Priority requested 15.11.82, US, US, No. 441979.

(54) DESCRIPTION OF THE INVENTION ANALOGY PROCEDURE FOR THE PREPARATION OF EPIMERT AZAHOMOERYTROMYCIN A AND BETWEEN PRODUCT FOR THE PREPARATION OF THIS.

<td>(57) Summary</td><td>Antibacterial 4-epi-9-deoxo-9a-methyl-9a-aza9a-homoerythromycin A, pharmaceutically acceptable salts thereof, pharmaceutical compositions containing antibacterially effective amounts thereof, a method of treating bacterial Infections with antibacterially effective amounts thereof, and intermedia tes by synthesis hence fr om erythromycin A.</td>

(56) Published Publications British (GB) Patent No. 2047247, 2094293.

1.60262

The present invention relates to a process for the preparation of antibacterial 4-epi-9-deoxo-9a-methyl-pa-aza-9ahomoerytromycin A, pharmaceutically acceptable salts thereof, and intermediates useful in the preparation thereof from erythromycin A.

Erythromycin A is a well-known macrolide antibiotic, having formula (I), which has found widespread clinical use.

<img file="NO160262B_D0001.tif" />

The present therapeutic compound is the 4-epimer of the previously reported erythromycin A derivative of formula (II),

<img file="NO160262B_D0002.tif" />

(II) R = methyl (III) R = hydrogen subject to Belgian patent 892,357, as well as my contemporaneous US application Serial No. 399,401, filed July 19, 1982. In the Belgian patent, the compound of formula (II) is named as Nmethyl the derivative of 11-aza-10-deoxo-10-dihydroerythromycin A, a name previously found by Kobrehel et al., U.S. Pa tent 4,328,334 to the prec ursor compound of formula (III). For the latter ring-expanded (homo), aza (nitrogen substituted for carbon) erythromycin A derivative, we prefer the name 9-deoxo-9a-aza-9a-homoerythromycin A. That compound could also be named as a 10-aza-14-hexadecanolide derivative .

Certain of the present novel intermediates are also 4-epimers of previously known compounds. Thus, the 4epi-9-deoxo-9a-aza-9a-homoerythromycin A is the 4-epimer of the above compound of formula (III); and 4-epi-erythromycin A oxime is the 4-epimer of erythromycin A oxime known from Djokic et al., U.S. Patent 3,478,014. 4-Epi-erythromycin A is the subject of simultaneously filed U.S. Patent Application Serial No. 353,547, filed March 1, 1982 by Sciavolino et al.

The present invention comprises the preparation of the antibacterial compound 4-epi-9-deoxo-9a-methyl-9a-aza9a-homoerythromycin A, which has the formula (IV), pharmaceutically acceptable salts thereof, which c an be used in the treatment of bacterial infections in mammals.

<img file="NO160262B_D0003.tif" />

(IV) R = methyl, Z = Z¹ = hydrogen (VI) R = 1- = hydrogen

The present therapeutic compound (IV) shows a relatively broad spectrum of antibacterial activity which includes erythromycin A-sensitive organisms and, in addition, completely incorporates the main respiratory pathogen Hemophilus influenzae. Its high oral absorption and extraordinarily long half-life in vivo make compounds (IV) particularly valuable in the oral treatment of susceptible bacterial infections in mammals.

The present invention also encompasses two novel intermediates useful in the synthesis of 4 '-epi-9-deoxo-9a-methyl-9aaza-9a-homoerythromycin A (IV) as follows:

(a) 4-epi-9-deoxo-9a-aza-9a-homoerythromycin A of formula (VI), (b) 9-deoxo-4-deoxy-4-oxo-9a-methyl-9a-aza 9ahomoerythromycin A, of formula (Vila);

<img file="NO160262B_D0004.tif" />

Another starting material used in the preparation of the compounds of formula IV is 4-epi-9-deoxo-9a-methyl-9a-aza9a-homoerythromycin A 3'-N-oxide, of formula (XI):

<img file="NO160262B_D0005.tif" />

According to the invention, 4-epi-9-deoxo9a-methyl-9a-aza-9a-homoerythromycin A or a pharmaceutically acceptable salt thereof is prepared by the following alternative methods:

(a) methylation of 4-epi-9-deoxo-9a-aza-9a-homoerythromycin A with formaldehyde in the presence of a reducing agent selected from formic acid, sodium cyanoborohydride, or hydrogen and a noble metal catalyst in a reaction-inert solvent at 20-100 ° C;

(b) N-deoxygenation of 4-epi-9-deoxo-9a-methyl-9a-aza ~ 9a-homoerythromycin A 3'-N-oxide with hydrogen over a noble metal or Raney nickel catalyst in a reaction inert solvent at 20-100 ° C; or (c) hydrogenation of 4-deoxy-4-oxo-9-deoxo-9amethyl-9a-aza-9a-homoerythromycin A over a noble metal or Raney nickel catalyst in a reaction-inert solvent at 20-100 ° C.

Since compound (IV) of the invention contains two basic nitrogen atoms, pharmaceutically acceptable mono and diacid addition salts are formed by contacting the free base (IV) with one equivalent of the acid or at least two equivalents of the acid, respectively. The salts are generally formed by combining the reagents in a reaction-inert solvent; if the salt is not precipitated directly, it is isolated by concentration and / or addition of a non-solvent. Appropriate pharmaceutically acceptable acid addition salts include but are not limited to those with HCl, HBr, HNO ^, HjSO ^, H0₂CCH₂CH₂C0₂H, cis- and trans -HC ^ CCHCHCC ^ H, CH ^ C ^ H and p-CH₃CGH₄SO₃H.

The antibacterial activity of compound of formula (IV) is demonstrated by measuring its minimum inhibitory concentration (MIC) in µg / ml against a variety of microorganisms in a brain-cardiac infusion medium (BHI). Generally, twelve 2-fold dilutions of the test compound are used, with an initial concentration of the test compound in the range of 50 to 200 µg / ml. The sensitivity (MIC) of the test organism is accepted as the lowest concentration of compound capable of providing complete protection of growth judged by vision control. A comparison of the activity of 4-epi-9-deoxo-9amethyl-9a-a2a-9a-homoerythromycin A (IV) with that of erythromycin A is shown in Table I.

TABLE I

In vitro activity of compound (IV)

<td>microorganism</td><td></td><td>Day</td><td> 1 '</td><td>MIC pq / ml Day</td><td> 2</td>

<td></td><td></td><td>A</td><td>B</td><td>A</td><td>B</td>

<td>Staph, aur.</td><td> 005</td><td> 0,05</td><td> ’ 0,20</td><td> 0,05</td><td> 0,39</td>

<td></td><td> 052</td><td> 0,10'</td><td> 0,20</td><td> 0,10</td><td> 0,39</td>

<td></td><td> 400</td><td> 3,12</td><td> 3,12</td><td> 6,25</td><td> 12,5</td>

<td>Staph, epi</td><td> 111</td><td> 0,05</td><td> 0,10'</td><td> 0,05</td><td> 0,20</td>

<td>Strep, faec.</td><td> 006</td><td> 0,78</td><td> 1 ,56</td><td> 0,78</td><td> 0,78</td>

<td> Streak, pyog.</td><td> 203</td><td> 0,025</td><td> 0,025</td><td> 0,025</td><td> 0,025</td>

<td>Strep, pneumo.</td><td> 012</td><td> 0,025</td><td> 0,025</td><td> 0,025</td><td> 0,025</td>

<td>E. Coli</td><td> 125</td><td>(A)</td><td> 6,25</td><td>(A)</td><td> 6,25</td>

<td></td><td> 129</td><td>(A)</td><td> 1,56</td><td>(A)</td><td> 6,25</td>

<td></td><td> 266</td><td>(a)</td><td> 3,12</td><td>(A)</td><td> 6,25</td>

<td></td><td> 470</td><td> 3,12</td><td> 0,78</td><td> 3,12</td><td> 0,78</td>

<td>Affix. pn.</td><td> 009</td><td>(a)</td><td> 12,5</td><td>(A)</td><td> 12,5</td>

<td></td><td> 031</td><td>(a)</td><td> 12,5</td><td>(A)</td><td> 12,5</td>

<td>Affix. Oxy.</td><td> 024</td><td>(a)</td><td> 12,5</td><td>(A)</td><td> 12,5</td>

<td>Past. mult.</td><td> 001</td><td> 1,56</td><td> 0,10</td><td> 1 ,56</td><td> 0,10</td>

<td>Serr. March</td><td> 017</td><td>(A)</td><td> 50</td><td>(A)</td><td> 50</td>

<td>Neiss. sic.</td><td> 000</td><td> 1 ,56</td><td> 0,20</td><td> 3,12</td><td> 0,39</td>

<td>Ent. Aerogen.</td><td> 040</td><td>(A)</td><td> 12,5</td><td>. (A)</td><td> 12,5</td>

<td>Ent. cloaca.</td><td> 009</td><td>(A)</td><td> 25</td><td>(A)</td><td> 25</td>

<td>Prov. strua.</td><td> 01 3</td><td>(A)</td><td> 50</td><td>(a)</td><td> 50</td>

<td>H. influ.</td><td> 012</td><td> 3,12</td><td> 0,39</td><td> 1,56</td><td> 0,39</td>

<td></td><td> 036</td><td> 6,25</td><td> 0,39</td><td> 3,12</td><td> 0,39</td>

<td></td><td> 038</td><td> 6,25</td><td> 0,39</td><td> 3,12</td><td> 0,78</td>

<td>H. influ.</td><td> 042</td><td> 1 ,56</td><td> 0,39</td><td> 1,56</td><td> 0,39</td>

<td></td><td> 051</td><td> 3,12</td><td> 0,39</td><td> 3,12</td><td> 0,78</td>

<td></td><td> 073</td><td> 3,12</td><td> 0,39</td><td> 3,12</td><td> 0,78</td>

<td></td><td> 078</td><td> 1,56</td><td> 0,39</td><td> 1 ,56</td><td> 0,39</td>

<td></td><td> 081</td><td> 3,12</td><td> 0,39</td><td> 3,12</td><td> 0,78</td>

(a) greater than 50

A Erythromycin A control B Compound (IV)

In addition, compound (IV) is tested in vivo by the well-known mouse protection test, or by microbiological (bio-sample) calculation of serum levels in a variety of mammals (e.g., mouse, rat dog). Using rats as test animals, compound (IV) has been shown to be particularly well absorbed after oral dosing, showing exceptionally high and prolonged serum levels.

For the treatment of systemic infections in animals, including humans, caused by sensitive microorganisms, compound (IV) is dosed at a level of from 2.5 to 100 mg / kg per day. per day, preferably 5-50 mg / kg / day in divided doses, or preferably at a single daily dose. Dosage variation can be made depending on the individual and depending on the sensitivity of the microorganism. These compounds are dosed orally or parenterally, the preferred method being orally. The sensitivity of the microorganisms isolated in the clinics is routinely controlled in clinical laboratories by the well-known plate method. Compound (IV) is generally the compound chosen when a relatively large zone of inhibition against the bacteria that caused the infection to be treated appears.

Preparation of optimal dosage forms will be methods well known in the pharmaceutical art. For oral administration, the compounds are formulated alone or in combination with pharmaceutical carriers such as inert solid diluents, aqueous solutions or various non-toxic organic solvents in such dosage forms as gelatin, capsules, tablets, powders, lozenges, syrups and the like. Such carriers include water, ethanol, benzyl alcohol; glycerine, propylene glycol, vegetable oils, lactose, starches, talc, gelatin, gums and other well-known carriers. For the parenteral dosage forms, for the above systemic use, they are dissolved or suspended in a pharmaceutically acceptable carrier such as water, saline, sesame oil or the like. Agents that increase solubility and dispersion quality can also be added.

For the tropical treatment of surface infections in animals, including humans, caused by sensitive microorganisms, the compound (IV) is formulated by methods well known in the pharmaceutical in lotions, ointments, creams, gels or the like at concentrations in the range of 5 - 200 mg / cm³ of the dosage form, preferably in the range of 10-100 mg / cm³. The dosage form is applied to

60.2 6 2 site of infection ad libitum, generally at least once a day.

The present invention is illustrated by the following examples. Unless otherwise specified, all operations are performed at room temperature; all solvent evaporation was carried out in a vacuum from a bath at 40 ° C or less; all set temperatures are in degrees Celsius; all thin layer chromatographs (tlc) were performed on commercial silica gel plates (using the eluent indicated in parentheses); and all solvent ratios are by volume. THF is used for tetrahydrofuran, and DMSO is used for dimethyl sulfoxide.

EXAMPLE 1

4-epi-erythromycin A-oxime (oxime of 4-epimer of (I))

4-Epi-erythromycin A (50 g, 0.0646 mol) was dissolved in

265 ml of pyridine. Hydroxylamine hydrochloride (112.2 g, 1.615 mol) was added and the slurry stirred for 16 hours. The reaction mixture was evaporated to a thick slurry, diluted with 300 ml of isopropanol, stirred well and filtered with 3 x 100 ml of isopropanol for washing. The filtrate and wash water were combined, evaporated to a water-soluble foam, and treated with ether to give crude title product as hydrochloride salt (100 g). The latter was purified by partitioning between CH 2 Cl 2 and aqueous NaHCO 3 adjusted to pH 9.5 with dilute NaOH. The aqueous layer was separated and washed with ethyl acetate then ether. All organic layers were combined, dried (NaSO4) and evaporated to give the title product as a white foam, 59.5 g; tlcRf 0.5 (60: 10: 1 CH₂Cl₂: CH₃OH: conc. NH? OH);¹ Hnmr (CDCl 3) delta 2.31 (6H, s, (CH₃)₂N-), 3.32 (3H, s, cladinose CH 2 O-).

Example 2 4-Epi-9a-aza-9a-homoerythromycin A (V)

The title product of the previous example (59.2 g, 0.0787 mol) was dissolved in 400 ml of acetone. A slurry of NaHCO 3 (60 g) in 225 ml of H₂0 was added. Methanesulfonyl chloride (36.3 g, 24.5 mml) in 50 ml of acetone was added portionwise over β

minutes, while the temperature was maintained below 30 ° by cooling bath. The mixture was stirred for 4.5 hours, acetone was evaporated, CH₂C1₂ (400 ml) was added to the aqueous residue and the pH adjusted to 5.6 with 6N HCl. The aqueous layer was separated, washed with two portions of CH 2 Cl 2 and then adjusted to pH 9.5 with 6N NaOH. The basic solution was extracted 2 x fresh CH₂C1₂, 1 x ethyl acetate and 1 x ether. The basic organic extracts were combined, dried (Na₂SO₄) and evaporated to give title product as an ivory foam, 41 g; tlc Rf 0.4 (60: 10: 1 CH₂C1₂: CH₃OH: conc. NH₄OH); ¹Hnmr (CDCl3) delta 2.27 (6H, s, (CH3) 2N-), 3.29 (3H, s, cladinose CH 2 O-); ¹³Cnmr (CDCl3, (CH₃&gt;₄Si International Standard) ppm 177.24 (lactone C = O), 163.53 (amide OO), 1.02.29 and 95.24 (C-3, C-5), 40.22 ((CH2 N-).

EXAMPLE 3

2'-O-acetyl-9-deoxo-9a-aza-9a-homoerythromycin A (2'-O-acetate of (III)).

9-Deoxo-9α-aza-9α-homoerythromycin A (10 g, 0.0136 mol; (III); U.S. Patent 4,328,334) was dissolved in 150 ml of CH₂C1₂Acetic anhydride (1.39 g, 1.28 ml, 0.0136 mol) was added and the mixture was stirred for 3 hours. The acylation was followed by tlc; to drive the reaction to completion, 0.25 ml of acetic anhydride and then 0.5 ml of acetic anhydride were added, with stirring.

1.5 and 1 hour respectively. The reaction mixture was diluted with H₂0 and pH adjusted to 11 with dilute NaOH. The organic layer was separated, dried (NaSO)₄), and evaporated to a foam,

The foam (10 g) was chromatographed on 300 g silica gel with 9: 1 CH₂C1₂: CH₃OH as eluent and controlled by tlc. A minor polar impurity (3.6 g) was eluted, followed by purified title product, isolated as a white foam, 2 g; tlc Rf 0.2 (90: 10: 1 CH₂C1₂: CH₃OH: conc. NH₄OH); ¹Hnmr (CDClj) delta 2.02 (3H, s, C-2'-OC-CH₂), 2.26 (6H, s, (CH₂N-), 3.35 (3H, s, cladinose CH₂O-) .

By the same method of replacing acetic anhydride with propionic anhydride, the corresponding 2'O-propionyl derivative was prepared.

EXAMPLE 4

2'-0-Acetyl-9-deoxo-9a-benzyloxycarbonyl-9a-aza2

9a-homoerythromycin A ((IX), R = acetyl)

The title product of the previous example (1.7 g, 0.00219 mol) was dissolved in 70 ml of 5: 2 THF: H₂The pH was adjusted to 8 with dilute NaOH. Carbobenzoxychloride (0.51 g, 0.427 ml, 0.003 mol) was added and the mixture was stirred for 2 hours with further addition of diluted NaOH as necessary to maintain pH = 8. Since tlc indicated that the reaction was not complete, more carbobenzoxychloride ( 0.3 ml) was added and the reaction continued for 3 hours, still maintaining the pH of 8. The reaction was quenched with excess H₂O and ethyl acetate, pH was adjusted to 9.6 and the aqueous layer washed with CH₂C1₂. The organic. layers were combined, dried (Na 2 O 4) and evaporated to a foam, 2.4 g. The foam was chromatographed on 85 g silica gel eluting with 170: 10: 1 CH₂C1₂: CH 2 OH: conc. NH? OH. Pure fractions were combined, evaporated to a foam, taken up in CH₂C1₂ and concentrated until the title product crystallized, 1.2g; mp. 122 °; tlc Rf 0.4 (90: 10: 1 CH₂Cl₂: CH₃OH: conc. NH? OH);

¹ Hnmr (CDCl3 delta 2.00 (3H, s, C-2 '-OC-CH2, 2.27 (6H, s, ^J 1 3 ³ (CH₃)₂N-), 3.35 (3H, s, cladinose CH₃O-); Cnmr (CDC1₃, (CH₃&gt;₄Si International Standard) ppm 176.31 (lactone C = 0), 169.36 (C-2¹ ester C = 0), 157.10 (carbamate C = 0); 137.0, 127.55 and

127.92 (aromatic ring); 40.6 {(CH₂N-).

By the same method, the 2'-O-propionyl derivative of the preceding example is converted to the corresponding 2'-O-propionyl-9α-benzyloxycarbonyl derivative.

EXAMPLE 5

2'-O-acetyl-9a-benzyloxycarbonyl-9-deoxo-4deoxy-4-oxo-9a-aza-9a-hemoerythromycin A ((VIII), R² = acetyl)

Oxalyl chloride (4.37 g, 3.0 ml, 0.0344 mol) was dissolved in 25 ml CH₂C1₂ and cooled to -60 °. DMSO (6.70 g, 6.09 ml, 0.0856 mol) in 9 ml CH₂C1₂ was added. After cooling the mixture at -60 ° for 10 minutes, the title product was from the preceding one

16'0262 Example (5.2g, 0.00572 mol) in 16ml added at the same temperature. After further 25 minutes at -60 °, triethylamiri (17.3 g, 23.9 ml, 0.172 mol) was added and the mixture was warmed to room temperature, diluted with 50 ml of H 2 O and excess NaHCO 3. separated, dried (Na-SO.)^f : · 2 4 and evaporated to give the title product as a sticky foam, 6.8 g; tlc Rf 0.6 (90: 10: 1 CH₂Cl₂: CH₂OH: conc. NH? OH);

¹Hnmr (CDCl 3 delta 2.05 (3H, s, C-2 '-OC-CH 2), 2.25 (6H, s,₃)₂N-), 3.32 (3H, s, cladinose CH 2 O-), 7.37 (5H, s, aromatic protons); MS: major peaks at m / e 536 and 518 (N-benzyloxycarbonyl aglycone ion (minus both sugars via division at C-1, C-5)), 200 (major peak, desosamine-derived fragment), 125 (neutral sugar derivative fragment). This intermediate is preferably used immediately in the next step.

Similarly, the corresponding 2'-O-propionyl4-oxo derivative was prepared from the 2'-O-propionyl compound of the preceding example.

Example 6 9a-Benzyloxycarbonyl-9-deoxo-4-deoxy-4-oxo9a-aza-9a-homoerythromycin A (VII)

The title product of the previous example, 1.0 g, was stirred in 25 ml of methanol for 65 hours, then evaporated to a foam. The foam was taken up in CH₂C1₂, washed with NaHCO3, and re-evaporated to a new foam. This new foam was chromatographed on 20 g of silica gel using 13: 1 CH₂C1₂: CH₃OH as the eluent. Pure product fractions were combined and evaporated to give purified title product as a foam, 336 mg; tlc Rf 0.4 (90: 10: 1 CH₂Cl₂: CH₃OH: conc. NH? OH;¹³Cnmr (CDClp (CH₃)₄ Si International Standard) ppm 210.87 (C-4 C = O), 176.03 (lactone C = O), 157.41 (carbamate C = O); 136.31, 128.2 and 128.0 (aromatic ring); 104.15 and 96.83 (C-3, C-5).

Alternatively, the title product of the previous Example (86 g) was stirred for 16 hours, then refluxed for 4 hours and evaporated to give the title product as a sticky foam, 6.2 g, indicating tlc (Rf and eluant as above) indicated sufficient purity to be used directly. in the next step.

Similarly, the same title product was prepared by solvolysis of 2'-O-propionyl ester from the previous example.

EXAMPLE 7

4-epi-9-deoxo-9a-aza-9a-homoerythromycin A (VI)

Method A

The title product of Example 2 (40 g) was dissolved in 600 ml of CH 2 OH. NaBH 3 (45 g) was added over a period of 45 minutes, keeping the temperature below 38 °. The reaction mixture was stirred for 64 hours, then evaporated to a thick slurry containing excess borohydride and boron ester complex of the product. The latter was distributed between 500 ml of each CH₂C1₂ and H₂O, and the following sequence was repeated three times: The pH was adjusted with stirring to constant pH 2.5 with dilute HCl; the mixture was stirred vigorously for 25 minutes; and the H 2 O layer was separated, combined with 500 ml of fresh CH₂C1₂, pH adjusted to

9.5 with dilute NaOH and CH₂C1₂ layer separated. pH 9.5 CH₂C1₂ the layer was combined with 500 ml of fresh H₂O for repeating the sequence. The third time the pH was 9.5 CH₂C1₂ layer dried (Na₂SO 2) and evaporated to give crude title product as a foam, 34 g, which was crystallized from 150 ml of hot isopropyl ether, cooled and diluted with 300 ml of pentane to give the purified title product, 25.8 g; white crystals; tlc Rf 0.5 (9: 1 CHCl3: dimethylamine); Rf 0.1 (90: 10: 1 CH₂Cl₂: CH₃OH: conc, NH 2 OH), m.p.

70 - 1 80°; ^{* 1 * * 4} Hnmr (CDCl3 delta 2.26 (6H, s, (CH2 N-)), 3.29 (3H, s, cladinose CH3O-); ¹³Cnmr (CDCl3, (CH₃)₄ Si International Standard) ppm 179.44 (lactone C = O), 103.57 and 96.70 (C-3, C-5); 41.50 ((CH₃)₂-N-).

Method B

Non-chromatographed title product of the previous example (6.2 g) was dissolved in 200 ml of ethanol and hydrogenated over 12.5 g of Raney Ni at 50 psi for 18 hours. The reaction mixture was filtered, 20 g of fresh Raney Ni added and hydrogenation continued for hours. Filtration and fresh catalyst addition were repeated, and hydrogenation continued for a further 16 hours. Filtration and evaporation of the filtrate gave crude title product as a white foam. The latter was partitioned between CH 2 Cl 2 and saturated

NaHCOβ and the organic layer separated, dried (Na 2 O / and evaporated to give the title product as another white foam, 3.6 g crystallized as above to give purified title product, 955 mg, which has physical properties identical to the product prepared by method A.

EXAMPLE 8

4-epi-9-deoxo-9a-hydroxy-9a-aza-9a? homoerythromycin A 3'-N-oxide (X)

By stirring below 1 / the title product of the previous example (3.0 g) was dissolved in 15 ml of 1: 1 THF: CH 2 OH. Thirty percent H₂O₂ (5 ml) was added. After 0.5 hours, another 30% l / C / (2.5 ml) was added. After a further 0.5 hours, the reaction mixture was gently poured into 1: 1 C / Cl / I / O containing excess Na₂SC / (exothermic). The pH was 9. The aqueous layer was washed with fresh C / C / and then ethyl acetate. The organic layer was combined, dried (Na₂SO / and evaporated to give the title product, 2.7 g, tlc Rf 0.15 (60: 10: 1 C / C / zC / OH: cons. NH₄OH); ¹ Hnmr (CDCl / delta 3.21 (6H, s, (CH 2 NO), 3.38 (3H, s, cladinose CH 2 O-); MS: main peak at m / e 576 (ion from desosamine fragmentation at C-5 ), 418 (N-hydroxyglyconion minus both sugars) Both peaks diagnostic of the -N-OH environment by aglycone.

EXAMPLE 9

4-epi-9-deoxo-9a-methyl-9a-aza-9a-homoerythromycin A

3'-N-oxide (XI)

The title product of the previous example (2.6 g,

0.0034 mol) was dissolved in 100 ml C / C /. During vigorous stirring, the^K2^CO3 &lt;37 »5 0.271 mol) and then C / I (19.3 g, 8.5 ml,

0.136 mol) was added and the mixture stirred for 20 hours. Filtration and evaporation gave the title product as a foam, 2.9 g; tlc Rf 0.3 (60: 10: 1 O / Cl 2 C / OHicon. NH 3 OH), Rf 0.15 (90: 10: 1 CI / C /: CH₃OH: conc. NH? OH).

The title product thus prepared (2.8 g) was further purified by chromatography on 85 g silica gel using 90: 10: 1

CH₉ci: CH-, OH: conc. ^z 2 ³

NI / OH as eluent;

and in this way remove less more polar impurities. Recovery: 0.87 g;¹ Hnmr (CDCl 3 delta 2.32 (3H, s, aglycon CH 3 -N-), 3.20 (6H, s, (CH₃)₂N-&gt; O), 3.37 (3H, s, cladinose CH2 O-).

EXAMPLE 10

4-epi-9-deoxo-9a-methyl-9a-aza-9a-homoerythromycin A (IV)

Method A

The title product of Example 7 (0.706 g, 0.96 mmol) was dissolved in 20 mL of CHCl 3. Formaldehyde (37%, 0.078 ml) and then formic acid (0.03 ml) were added and the mixture was stirred for 4 hours, then refluxed for 7 hours. The reaction mixture was cooled, added to 30 ml of H₂O and adjusted to pH 9 with 6N NaOH. The organic layer was separated, dried (Na₂SO₄&gt; and evaporated to give the title product as a white foam 0.7 g; crystallized from hot ethanol / H 2 O, 302 mg, m.p. 153 °; recrystallized from hot ethanol / H₂0, 246 mg; mp. 155 °; tlc Rf 0.55 (60: 10: 1 CH₂C1₂: CH₃OH: conc. NH ^OH), Rf 0.6 (9: 1 CHCl-: diethylamine);¹Hnmr (CDCl₃) delta 2.29 (9H, broad s, aglycone N-CH₇ and desosamine (CH-JN-), ^{JJ i}

3.31 (3H, s, cladinose CH₃O-); Cnmr (CDClj, CDCl1)₃ International Standard) ppm 178.89 (lactone C = O), 102.63 and 95.15 (C-3, C-5), 40.38 ((CH₃)₂N-); MS: main peak at m / e 590 (N-methyl aglycone desosamination via cladinose cleavage at C-1), 416 (Nmethyl aglycone ion (minus both sugars via cleavage at C-1, C-5)), 158 (main peak, deosaminderivat fragment).

Method B

Non-chromatographed title product of the previous example (0.242 g) and 10% Pd / C (0.4 g) were combined in 15 ml of 95% ethanol and the mixture hydrogenated at 50 psig for 1 hour. Catalyst was removed by filtration and the filtrate evaporated to give the title product as a white foam, 160 mg, crystallized from ether / pentane, 124 mg, recrystallized from ethanol / H₂0, 95 mg, have physical properties identical to the title product of Method A.

Method C

Chromatographically purified title product from the previous example (319 mg) and Raney nickel (1.5 g, 50% water-humidified) were combined in 20 ml of ethanol and hydrogenated at 50 psig for 1.5 hours. Catalyst was removed by filtration and the mother liquor evaporated to dryness to give 205 mg of title product, identical in physical properties to the title product of Method A.

EXAMPLE 11

2'-O-acetyl-9-deoxo-9a ~ methyl-9a-aza-9ahomoerythromycin A

The title product of Preparation 5 (2.5 g ', 3.34 mmol) was stirred with acetic anhydride (0.339 ml, 3.60 mmol) in 30 ml CH₂C1₂for 4 hours. The reaction mixture was evaporated and the residue dissolved in 50 ml of ethyl acetate, combined with 50 ml of H₂0 and pH adjusted to 9.5 with 1N NaOH. The aqueous layer was separated and washed with 20 ml of fresh ethyl acetate. The organic layers were combined, dried (NaSO4), evaporated, dissolved in 30 mL of CHCl4 and evaporated once more to give the title product as a solid, 2.82 g, 3 Hnmr / CDCl3 include delta 3.31 ( C4-OCH.p, 2.28 (N-CH2), 2.25 (N- (CH₃)₂) and 2.0 (Σ'-ΟΟΟΟψ.

EXAMPLE 12

2'-O-acetyl-4-deoxy-4-oxo-9-deoxo-9a-methyl9a-aza-9a-homoerythromycin A (Villa)

The title product of the previous example (2.5 g, 3.2 mmol) and DMSO (0.38 ml, 5.23 mmol) were dissolved in 90 ml CH₂C1₂and cooled to -70 ° C. While maintaining a temperature lower than -50 ° C, trifluoroacetic anhydride (0.72 ml,

4.95 mmol) added by syringe and the mixture stirred for 50 minutes at -60 °. Triethylamine (1.54 ml, 11 mmol) was added by syringe, maintaining temperature lower than -50 ° during the addition. The mixture was then warmed to 0 °, diluted with._:H₂O and pH adjusted to 9.5 with dilute NaOH. The organic layer was separated, dried (NaSO4) to give the title product as a foam, 2.5 g. The foam was rapidly chromatographed on silica gel with 10: 1 CHCl4 .CH2OH as eluent, monitored at tlc and collected in 3 fractions. Purest product fraction 1, 1.7 g, was dissolved in CHCl 3, diluted with H₂0, adjusted to pH 4 with dilute HCl, and the aqueous layer separated, diluted with fresh CHCl3, adjusted to pH 8 with dilute NaOH and the organic layer separated. The final aqueous layer was extracted with three portions of fresh CHC1₃. The last four organic layers were combined, washed with H₂O, dried (Na₂SO)) and evaporated to give purified title product, 0.98g; tlc Rf 0.7 (5: 1: 0.1 CHCl₃: CH₃OH: NH₄OH); ¹Hnmr (CDCl₃) includes delta (ppm): 2.05 (s, 3H, COCH₃), 2.26 (s, 6H, N (CH₃&gt;₂), 2.33 (d, 3H, NCH.j) and 3.33 (d, 3H, OCH

EXAMPLE 13 4-Deoxy-4-oxo-9-deoxo-9a-methyl-9a-aza-9ahomoerythromycin A (Vila)

The title product of the previous example (0.93 g) was dissolved in methanol. After 20 minutes the mixture was evaporated to give the present title product, 0.74 g; ms 746.4, 588.4, 573.4, 413.3, 158.1, 125.1;¹Hnmr (CDCl₃) includes delta (ppm): 5.5 (t, 1H, C1-H), 4.6 (q, 1H, C5-H), 3.35 (s, 3H, AND₃), 2.38 (s, 3H, NCH₃), .. 2.30 (s, 6H, N (CH-j)) ₂ ).

EXAMPLE 14 4-Epi-9-Deoxo-9a-methyl-9a-aza-9a-Homoerythromycin A (IV)

The title product of the previous example (0.25 g) and

250 Raney nickel mg was combined in 20 ml ethanol and hydrogenated under 50 psig for 4 hours. The catalyst was removed by filtration and the filtrate evaporated to an oil which crystallized on standing. The title product was recovered by treatment with isopropyl ether and filtration, 0.13 g, identical to those of the product of Example 10.

PREPARATION 1

4 '* - epi-erythromycin A

A suspension of 100 g of Raney nickel in 1 liter of absolute ethanol containing 100 g of 4-deoxy-4-oxoerythromycin A (US 4,510,220) was shaken in a hydrogen atmosphere overnight at room temperature at 50 psig. The spent catalyst was filtered over diatomaceous earth and the filtrate was concentrated in vacuo

300 ml ·. . Water (700 ml) was added to the concentrated filtrate and the resulting milky solution was heated on a steam bath. A small amount of ethanol was added to prevent rubberization of the product when precipitated from the solution. After stirring for 2 hours at room temperature, the product was filtered and dried, 57.6 g, and the filtrate concentrated in vacuo to the point of fog. The mixture was allowed to stir for 1 hour and filtered, and dried, 21.4 g.

The resulting solids were combined, m.p. 141 144 ° C.¹The Hnmr spectrum (CDCip showed absorption at 3.3 (3H,

s), 2.3 (6H, s) and 1.4 (3H, s) ppm.

PREPARATION 2

Erythromycin A oxime hydrochloride

Under N₂, erythromycin A (500 g, 0.681 mol) was dissolved in pyridine (2,787 kg, 2,850 L, 35.29 mol). Hydroxylamine hydrochloride (1.183 kg, 17.02 mol) was added and the mixture stirred for 22 hours, then evaporated to a thick slurry and filtered with isopropanol washing. The combined filtrate and the wash water were again evap orated to a thick, waxy mass, which crystallized by treatment with 2 L of water, 615 g, (slightly watery, used in the next step without further drying); tlc Rf 0.45 (60: 10: 1 CH₂Cl₂CH₃OH: conc. NH? OH).

- By the same procedure, 5 g of erythromycin A was converted to dried title product, 4.5 g, at least 95% pure at³C NMR. Recrystallization of 1 g from 10 ml. methanol and 30 ml of isopropyl ether gave 725 mg; mp. 187 ° (dec.) (Literature mp 188-191 °, Massey et al, Tetrahedron Letters, pages 157-160, 1970);¹³Cnmr (DMSO-d 6, (CH₄ Si International Standard) ppm 174.35 (lactone C = O), 168.78 (C = N-), 101.0 and 95.46 (C-3, C-5).

PREPARATION 3

9a-aza-9a-homoerythromycin A

In the procedure of Example 2, with gas evolution by the addition of the bicarbonate, the slightly water-moist title product of the preceding preparation (61'5 g, calculated to be 506 g, 0.613 mole on a dry basis) was conve rted to crystalline title product.

416 g; Cnmr (CDCl3, CDCl3 international standard) ppm 177.54 (lactone C = O), 163.76 (amide C = 0), 102.28. and 94.20 (C-3, C-5), 40.13 ((CH₃)₂N-).

PREPARATION 4

9-deoxo-9a-aza-9a-homoerytroniycin A

By reduction with NaBH ^ according to the method of Kobrehel et al. (supra), the title product of the previous preparation was converted to the present title product.

PREPARATION 5

9-Deoxo-9a-methyl-9a-aza-9a-homoerythromycin A

In the procedure of Example 10 above, the title product of the preceding preparation (21.1 g, 0.0287 mol) was converted to the present title product, first isolated as a white foam, crystallized from hot ethanol / F₂O, 18.0 g. , m.p. 136 ° C.