IE46624B1 - Intermediates useful in the preparation of n-monosubstituted-9-amino-9-deoxyclavulanic acid derivatives - Google Patents

Description

The present invention relates -to intermediates useful in the synthesis of β-lactam antibacterial agents, and tothe process for their preparation.

British Patent Application No. 41887/75 (see also 5 Belgian Patent No. 847004 and West German Offenlegungsschrift No. 2646003 discloses inter alia the compounds of the formula (I): and esters thereof wherein X^ is hydrogen atom, an alkyl group of up to 5 carbon atoms, an alkenyl group of up to carbon atoms, a hydroxy alkyl group of up to 5 carbon atoms or an optionally substituted phenyl group and X2 is an optionally substituted phenyl group, such compounds were described, as antibacterial agents and β-lactafliase inhibitors. ι It has -new-been discovered that certain secondary amines can be prepared that are β-lactamase inhibitors that enhance the effectiveness of penicillins or cephalosporins and which also have antibacterial properties in their own right.

Patent Specification No. $6623 provides a compound 20 · of the formula (II)s Z~N H2-NH-CH2-R1 έθ2Η (II) or an ester thereof wherein R^ is a hydrogen atom, an alkyl group of up to 5 carbon atoms, a cycloalkyl group of 5 or 6 carbon atoms, a hydroxyalkyl group of up to 5 carbon atoms or a moiety of the sub-formula (a): wherein R2 is a hydrogen, fluorine, chlorine or bromine atom or an alkyl group of 1-3 carbon atoms, an alkoxyl group of 1-3 carbon atoms, an acyloxy group of 1-3 carbon atoms, a hydroxyl group, an alkoxycarbonyl group containing 1-3 carbon atoms in the alkoxy part, or a group -N(Rg)CO.Rg, -N(Rg)SO2Rg or -CO-NRgRg where Rg is a hydrogen atom or an alkyl group of 1-3 carbon atoms or a phenyl or benzyl group and Rg is an alkyl group of 1-3 carbon atoms or a phenyl or benzyl group; R^ is a hydrogen, fluorine or chlorine atom , a hydroxyl group, an alkyl group of 1-3 carbon atoms, an alkoxy group of 1-3 carbon atoms or an acyloxy group of 1-3 carbon atoms; and R^ is a hydrogen,fluorine or chlorine atom, an alkyl group of 1-3 carbon atoms or an alkoxy group of 1-3 carbon atoms.

Patent Specification No. 'V-ViA^S also provides a process for the preparation of an ester of a .compound of the formula (II) which process comprises the hydrogenation of a corresponding ester of a compound of the formula (III): wherein is as defined, in relation to formula (II) and Ry is a group of sub-formula (a) as defined in relation to formula (II).

The present invention provides compounds of formula (III) and salts and esters thereof.

Most suitably Ry is a phenyl group.

Suitably the compounds of formula (III) are in the form of a salt such as an alkali metal salt, for example the lithium salt.

The ester of the compound of the formula (III) is suitably an alkyl ester of 1 to 6 carbon atoms optionally substituted by an alkoxyl or acyloxyl group of 1 to 7 atoms Particularly suitable formula (III) include C^_4 methyl and ethyl esters. esters of the compound of the alkyl esters especially the The present invention also provides a process for the preparation of a compound of the formula (III) or a salt or ester thereof which process comprises the reaction of a compound of the formula (II), or a salt thereof, as here5 inbefore defined, with a compound of the formula (IV): Y - CO - O - 0¾¾ (IV) wherein R^ is as defined in relation to formula (II) and Y is a readily displaceable group, and thereafter where necessary esterifying the free carboxylic group or a salt thereof.

Favoured groups Y include the chlorine atom and chemically equivalent atoms or groups such as the bromine atom or a OR? group.

A preferred compound of the formula (IV) is benzylchloroformate .

The reaction may be performed under conventional acylation conditions, for example in non-acylatable organic solvent such as acetone in the presence of an acid acceptor such as lithium carbonate, sodium carbonate or potassium carbonate at a non-extreme temperature such as-10° to 30°C, for example at 0° to 10°C.

We have found it convenient to carry out the acylation on a salt of the compound of the formula (II) such as an alkali metal salt and in particular the lithium salt.

The esterification step is suitably effected by the reaction of a salt of a compound of the formula (III) with a reactive halide or the chemical equivalent thereof.

Suitable salts of the compound of the formula (XII) include the lithium’, sodium and potassium salts. Suitable esterifying agents include reactive chlorides, bromides, iodides, acid anhydrides, tosylates and mesylates.

The esterification may be effected in a conventional organic solvent such as acetone or dimethylformamide. The reaction is normally effected at a non-extreme temperature such as 0° to 35°C, for example 10° to 25°C. Conveniently the reaction is performed at ambient temperature.

The acid of the formula(lll) may also be esterified by reacting with an alcohol in the presence of a condensation promoting reagent, such as a carbodiimide, for example dicyclohexylcarbodiimide, or the chemical equivalent thereof. Such reactions may be carried out under conditions similar to those hereinbefore described for the same type of reaction carried out on an acid addition salt of a compound of the formula {II).

We have chosen to. name the novel compounds of this invention as notional derivatives of deoxyclavulanic acid which is one of the formula (V): thus on this system the amino-substituent is defined as being attached to the 9-carbon atom.

The following Examples illustrate the invention. 6 6 2 4 EXAMPLE 1 (a) Benzyl 9-(N,N-dibenzyl)aminodeoxyclavulanate Benzyl dichloroacetyl-clavulanate (0.8g) was dissolved in dry dimethylformamide and cooled to 0°C, treated with dibenzylamine (768μ1; 0.004 mol) in dry dimethylformamide (4ml) over 15 minutes, the temperature being maintained at 0°C.

The resulting yellow solution was stirred at 0° for 2| hours and at room temperature for 4 hours. Ethylacetate was added (100ml) and the solution washed with water (3 x 25ml), dried and evaporated. The oil was purified by fast gradient elution on silica gel using ethyl acetate/cyclohexane as the eluting solvent (Yield 0.33g). Rf (SiO2/ethylacetate:cyclohexane; 1:1) = 0.76. V(film) 1810, 1755, 1700; &(CDC13) 2.80 (1H, d, J 16Hz, ββ-CH) 3.05 (2H, d, J 7Hz, 9-CH2), 3.17-3.37 (1H, m, 6a-CH) 3.32 (4H, s, 2 x NCH2C6H5), 4.59 (1H, t, J 7Hz, 8-CH), 4.90 (1H, s, 3-CH), 5.03 (2H, s, OCH2CgH5) 5.57 (1H, d, J 3Hz, 5a-CH), 7.20 (15H, s, 3 x CgH5). (b) 9-N-Benzylaminodeoxyclavulanic acid Benzyl 9-(N,N-dibenzylamino)deoxyclavulanate (0.43g) in ethanol and tetrahydrofuran, 1:1 (75οώ*) with 1cm^ water was hydrogenated with 5% palladium on carbon (0.43g) as catalyst. The hydrogenation was carried out at 55 psi for 5 hours. The mixture was filtered through Celite (Registered Trade Mark) and the clear filtrate evaporated in vacuo to yield a coloured oil. This oil was dissolved in ethyl acetate (80οπΛ) and washed with water (3 x 30cm^). The combined aqueous extracts were evaporated in vacuo to yield a pale yellow oil. This oil was chromatographed on a cellulose column, eluting with butanol/propan-2-ol/water; 4:4:1. Fractions were collected containing 9-N-benzylaminodeoxyclavulanic acid,detection hy aqueous potassium permanganate spray; Rf (SiO?; butanol/propan-2-ol/water, 7:7:6) = 0.45.

The combined fractions were evaporated in vacuo to yield a solid. This solid was washed with ethanol and then dried to yield 9-N-benzylaminodeoxyclavulanic acid (36mg). V(KBr) (3680-3150 (3100-2900), (2900-2300), 1800, 1694, 161O, 1460, 1400, 1305, 1190, 1020, 895, 755, 700 cm-1; S(D20 + 5% DMSO D-6), 3.13 (1H, d, J 17Hz, 6β-0Η), 3.62 (1H, bd, J 17Hz, 6a-CH), 3.77 (2H, d, J 8Hz, 9-CH2), 4.22 (2H, s, CH2C6H5), 4.84 (1H, t, J 8Hz, 8-CH), .01 (1H, s, 3-CH), 5.77 (1H, bs, 5«-CH), 7.48 (5H, s, CgHj).

The compound of this invention was produced as fine needles, (ie. in crystalline form). Crystalline 9-N-benzylaminodeoxyclavulanic acid is normally colourless. Chemical Analysis of the product indicated that the crystals contained water. 4662 (c) Lithium 9-N-carbobenzoxv-N-benzylaminodeoxyclavulanate 9-N-Benzylaminodeoxyclavulanic acid (1.15g) in dimethyl formamide (20ml) containing one equivalent of lithium bicarbonate (544mg; 10.8ml 5% solution) was treated dropwise with a solution of benzylchloroformate (684mg) in acetone (10ml) at 0°. The reaction mixture was stirred at this temperature for 1 hour. The solvent was removed and the residue triturated with acetone/ether, ine resulting white solid lithium 9-N-carbobenzoxy-N-benzylaminodeoxyclavulanate was filtered off and dried in a desiccator in vacuo (1.6g), Rf (Si02: n-butanol: isopropanol: water; 7:7:6) 0.66; [a = + 28.3° (C=1.6; water); VmaX (nujol) 1778, 1682, 1620cm1, S ((CD3)2 SO) 2.68 (1H, d, J 17.5Hz, ββ-CH), 3.42 (1H, dd, obscured by water peak, 6a-CH), 3.8 (2H, d, J 7-5Hz, 9-CH2), 4.32 (2H, s, NCHgC6H5), 4.52 (2H, m, 3-CH and 8-CH), 5.07 (2H, s, N.C0.0.CH2), 5-52 (1H, d, J 3Hz, 5-CH), 7.21 (5H, s, aromatic-H), 7.28 (5H, s, aromatic-H).

Example 2 Methyl 9-N-carbobenzoxv-N-~benzvlaminodeoxyclavulanate Lithium 9-N-Carbobenzoxy-N-benzylaminodeoxyclavulanate (428mg) was dissolved in dimethylformamide (10ml) and methyl iodide (710mg) added. The reaction mixture was stirred at room temperature for 4 hours. The solvent was removed and the residue chromatographed on silica gel eluting with ethyl acetate: cyclohexane (1:1). The title compound was obtained after evaporation of the solvent as a colourless oil (244mg).

Rf (Ethylacetate-cyclohexane; 1:1) = 0.75; [α]^θ= + 13.21° (C=1.12; MeOH); „ (film) 1805, 1750, 1690 cm-1; £(CDCl,) UlcLX 2 2.86 (1H, d, J 17.5HZ, δβ-CH), 3.42 (1H, dd, J 17.5 and 3Hz, 6a CH), 3.72 (3H (3H, s, COgCH^), 3.96 (2H, d, J 7.5Hz, CH.CH2N), 4.44 (2H, s, NCH2Ph),' 4.67 (1H, bt, J 7.5Hz, CHCH2), 4.94-(1H, d, J 1.5Hz, 3-CH), 5.16 (2H, s, COgCHgPh), 5.53 (1H, d, J 3Hz, 5-CH), 7.22, 7.3 (10H, 2 x s, Ar-H). 6 6 2 4 Example 3.

Ethyl 9-N-carbobenzoxv-N-benzylaminodeoxyclavulanate Ethyl iodide (780mg) was added to a solution of lithium 9-N-carbobenzoxy-N-benzylaminodeoxyclavulanate (428mg) in dimethylformamide (10ml) containing about 2 drops water.

The solution was allowed to stir at room temperature for seven hours. The solvent was removed by evaporation and the residue chromatographed on silica gel. The product was isolated by elution with ethyl acetate: cyclohexane; 1:1 and was obtained after evaporation of the solvent as a colourless oil (3O7mg). Rf (ethyl acetate: cyclohexane; 1:1) = 0.78; [α]^°= + 9,6° (c=1*385 MeOH); Vmax (film) 1802, 1745, 1695 cm1 S (CDClj) 1.25 (3H, t, J 8Hz, CH2CH3), 2.86 (1H, d, J 17.5Hz, δβ-CH), 3.41 (1H, dd, J 17.5Hz and 3Hz, 6 8Hz, CHCH2N), 4.17 (2H, q, J 8Hz( CH2CH3), 4.43 (2H, s, NCH2CgH5), 4.92 (1H, d, J 1.5Hz, 3-CH), 4.67 (1H, bt, J 8Hz, 8-CH), .17 (2H, s, C0.0.CH2CgH5), 5.53 (1H, d, J 3Hz, 5-CH), 7-23, 7.30 (10H, 2 x s, Ar-H). n 6 624 Example 4 , Benzyloxycarbonylmethyl 9-N-berizyloxycarbonvl-N-benzylaminodeoxyclavulanate 9-N-Benzyloxycarbonyl-N-benzylaminodeoxyclavulanic acid lithium salt (428 mg) was suspended in dimethylformamide (15 ml) and three drops of water added; benzyl bromoacetate(343 mg) was added to the resulting solution and the reaction mixture stirred at room temperature for five hours. Thin layer chromatography showed the reaction to be complete, the solvent was removed and the residue chromatographed on silica gel, eluting with ethyl acetate/cyclohexane (1:1). The combined fractions were evaporated in vacuo to yield a colourless oil (384 mg). Rf (Si02: ethyl acetate cyclohexane, 1:1) = 0.71; Ccc]^° = + 12.2° (C = 1.16; MeOH); Vmax (film) 1805, 1750 (b), 1705 (sh), 1690 cm-1; S(CDC13) 2.86 (1H, d, J 17.5HZ, ββ-CH), 3.58. (1H, dd, J 17.5 and 3Hz, βα-CH), 3.94 (2H, d, J 8Hz, 9-CH2). 4.44 (2H, s, NCHgPh), 4.65 (2H, s, C02CH2C02), 4.74 (1H,bt,partially obscured by signal at 4.65), 5.04 (1H, d, J, 1.5Hz, 3-CH), 5.15 (4H, s, NC02CH2Ph and CHgCOgCHgPh), 5.52 (1H, d, J 3Hz, 5-CH), 7.22, 7-29 (15H, 2 x s, aromatic -H).

Example 5 2-Hydroxyethyl 9-N-benzvloxycarbonyl-N-benzylamlnodeoxyclavuIanate 2-Iodoethanol (860 mg) was added to a solution of lithium 9-N-benzyloxycarbonyl-N-henzylaminodeoxyclavulanate (428mg) in dimethylformamide (15 ml) and water (3 drops). The solution was stirred for 14 hours at room temperature and the solvent removed; the residue was purified by column chromatography on silica gel, eluting with ethyl acetate/cyclohexane, 1:1. The product was obtained as a colourless oil. Rf (Si02: ethyl acetate:cyclohexane, 1:1) = 0.29', ^max (film) 1800, 1745, 1700 cm u · -r. 4 6 6 2 4 eiAIMSi-

Claims (7)

1. A compound of the formula (ill) or a salt or ester thereof: CH 2 R 1 CO-O-CH 2 R 7 wherein R^ is a hydrogen atom, an alkyl group of up to 5 carbon atoms, a cycloalkyl group of 5 to 6 carbon atoms, a hydroxyalkyl group of up to 5 carbon atoms or a moiety of the sub-formula (a): wherein R 2 is a hydrogen, fluorine, chlorine or bromine atom or an alkyl group of 1-3 carbon atoms, an alkoxyl group of 1-3 carbon atoms, an acyloxy group of 1-3 carbon atoms, a hydroxyl group, an alkoxycarbonyl group containing 1-3 carbon atoms in the alkoxy part, or a group -N(Rg)CO.R g -N(Rg)SO 2 Rg or -CO-NRgRg where Rg is a hydrogen atom or an alkyl group of 1-3 carbon atoms or a phenyl or benzyl group and Rg is an alkyl group of 1-3 carbon atoms or a phenyl or benzyl group; Rg is a hydrogen, fluorine or chlorine atom, a hydroxyl group, an alkyl group of 1-3 carbon atoms, an alkoxy group of 1-3 carbon atoms or an acyloxy group of 1—3 carbon atans; and R^ is a hydrogen, fluorine or chlorine aton, an allyl group of 1 to 3 carbon atans or an alkoxy group of 1 to 3 carbon atans); and Ry is a moiety of the sub-formula (a) as defined above. 1 4

2. A compound as claimed in claim 1 wherein Ry is a phenyl group.

3. A compound as claimed in claim 1 or 2 in the form of an ester.

4. A compound as claimed in claim 1 or 2 in the form of an alkali metal salt.

5. A compound as claimed in claim 1 or 2' in the form of the lithium salt.

6. A compound as claimed in claim 1, as described in any of Examples 1 to 6.

7. A process for the preparation of a compound, as claimed in claim 1 or a salt or ester thereof which process comprises the reaction of a compound of the formula (II) or a salt thereof: / N co 2 h (II) wherein R^ is as defined with respect to formula (IV) with a compound of the formula (V): y-co-o-ch 2 -r 7 (V) wherein Ry is as defined in relation to formula (IV) and Y is a readily displaceable group, and thereafter where necessary esterifying the free carboxyl group or a salt thereof. A process as claimed in claim 1 or bromine atom or a group OR?, in relation to formula (IV). wherein Y is a chlorine wherein R? is as defined 9. A process as claimed in claim 1 or claim 2 wherein the compound of formula (V) is benzylchloroformate.