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(11) | EP 0 000 828 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Synthetic beta-lactam compounds, a process for their preparation and compositions containing them |
| (57) This invention provides synthetic β-lactam antibacterial compounds, a process for
their preparation and pharmaceutical compositions containing them. The compounds are
those of the formula (II):
wherein: R1 is a group such that CO2R1 is a carboxylic acid group or a salt or ester thereof; and R2 is a phenyl group or a phenyl group substituted by one to four groups selected from lower alkyl, fluorine, chlorine, bromine, CN, NO2, COR3, OR3, SR3, NH2, NHCOR3, NHCO2R3, CO2R3 or CO2R1 where R3 is lower alkyl, benzyl, fluorobenzyl, chlorobenzyl, bromobenzyl or nitrobenzyl and CO2R10 is carboxyl or a salt thereof, not more than three such groups being selected from fluorine, chlorine, bromine, CN, NO2, NH2, COR3 or CO2R3 and not more than two auch groups being selected from CN, NO2 or NH2. |
[0001] The present invention relates to β-lactam antibacterials, to a process for their preparation and to compositions containing them.
[0002] British Patent No. 1483142 and J. Chem. Soc., Chem. Comm., 1977, 523 disclose that the compound of the formula (I).
and its salts may be obtained by fermentation of strains of Streptomyces olivaceus. We have now found that a distinct class of synthetic antibacterial agents which contain a β-lactam ring fused to a pyrroline ring may be prepared.
[0003] Accordingly, the present invention provides the compounds of the formula (II):
wherein:
R1 is a group such that CO2R1 is a carboxylic acid group or a salt or ester thereof; and
R2 is a phenyl group or a phenyl group substituted by one to four groups selected from lower alkyl, fluorine, chlorine, bromine, CN, N02, COR3, OR3, SR3, NH2, NHCOR3, NHCO2R3, CO2R3 or CO2R10 where R3 is lower alkyl, benzyl, fluorobenzyl, chlorobenzyl, bromobenzyl or nitrobenzyl and CO2R10 is carboxyl or a salt thereof, not more than three such groups being selected from fluorine, chlorine, bromine, CN, NO2, NH2, COR3 or C02R3 and not more than two such groups being selected from CN, N02 or NH2.
[0004] An apt group of compounds within formula (II) includes those wherein:
R1 is a group such that CO2R1 is a carboxylic acid group or a salt or ester thereof; and
R2 is a phenyl group or a phenyl group substituted by one or two groups selected from lower alkyl, fluorine, chlorine, bromine, CN, NO2, COR3, OR3, NHCOR3, NHCO2R3, or CO2R3 where R3 is a lower alkyl or benzyl group.
[0005] When used herein the term "lower" means that the group so described contains 1-4 carbon atoms.
[0006] A further apt group of compounds within formula (II) includes those wherein:
R1 is a group such that CO2R1 is an ester group; and
R2 is a phenyl group or a phenyl group substituted by one or two groups selected from fluorine, chlorine, bromine, CN, NO2, COR3, OR3, NHCOR3, NHCO2R3 or CO2R3 where R3 is a lower alkyl or benzyl group.
[0007] Suitable esterifying groups R1 include alkyl groups of up to 12 carbon atoms, alkenyl groups of up to 12 carbon atoms, alkynyl groups of up to 12 carbon atoms, phenyl or benzyl groups or any of the aforesaid inertly substituted by lower alkoxyl, lower acyloxyl,halogen, nitro or the like.group. Used herein 'inertly substituted' means that the resulting group is stable and will not undergo rapid decomposition.
[0008] Particularly suitable esterifying groups R1 include lower alkyl groups optionally substituted by lower alkoxyl, the benzyl group optionally substituted by lower alkoxyl, nitro, chloro or the like,and those groups which are known to give rise to rapid in-vivo hydrolysis in penicillin esters.
[0009] Certain preferred esterifying groups R1 include methyl, ethyl, methoxymethyl, 2-methoxyethyl, benzyl, methoxybenzyl, nitrobenzyl and the like.
[0010] Other particularly preferred esterifying groups R1 include those which give rise to in-vivo hydrolysable esters such as acetoxymethyl, pivaloyloxymethyl, α-ethoxycarbonyloxyethyl, phthalidyl and the like. A preferred group R1 of those giving rise to in-vivo hydrolysable esters is the phthalidyl group.
[0013] When CO2R1 is a carboxylic acid salt in compounds of the formula (II) also containing the group CO2R10, then C02R10 is usually also a carboxylic acid salt, and normally R1 and R10 are like cations.
[0014] Typical of salts of compounds of formula (II) are conventional pharmaceutically acceptable salts such as the alkali metal and alkaline earth metal salts, in particular the sodium, potassium, calcium and magnesium salts; ammonium and substituted ammonium salts, for example the t-butylamine salt..
[0017] Suitable groups R2 include the phenyl, p-chlorophenyl, m-chlorophenyl, p-nitrophenyl, m-nitrophenyl, p-ethoxy- carbonylphenyl, p-fluorophenyl, p-methylphenyl, p-aminophenyl, p-acetamidophenyl, p-(4'-nitrobenzyloxycarbonyl- amino)phenyl, p-methoxyphenyl and like groups.
[0018] The compounds of the formula (II) are most easily provided as mixtures of those having the R- and S- configuration at C-5 i.e. the 5R and 5S forms (For example formula (III):
[0019] depicts the S-configuration). However this invention also provides the separate 5R and 5S forms.
[0020] A preferred sub-group of compounds within formula (II) is of formula (IV):
wherein:
R11 is a group such that CO2R11 is an ester group of the type which is known to undergo rapid in-vivo hydrolysis in penicillin esters; and
R2 is as defined in formula (II).
[0021] Suitable groups R11 include acetoxymethyl, pivaloyloxymethyl, α-ethoxycarbonyloxyethyl, phthalidyl and the like. R11 is preferably phthalidyl.
[0023] A second preferred sub-group of compounds within formula (II) is of formula (V):
wherein:
R21 is a group such that the compound of formula (V) is a carboxylic acid salt; and
R2 is as defined in formula (II).
[0026] A sub-group of compounds within formula (II) of interest is of formula (VI):
wherein:
R31 and R12 are as in the Examples hereinafter.
[0043] The process provided by this invention for the preparation of the compounds of the formula (II) comprises
a) the ring closing elimination of the elements of 0 = PR4R5R6 from a compound of the formula (VII):
wherein CO2R41 is an ester group, as defined in relation to formula (II) and R4, R5 and R6 are each lower alkyl, phenyl or diloweralkylamino groups,,
b) thereafter isolating the ester of the formula (II) so formed,
c) where desired de-esterifying the ester to form a free acid or its salt,
d) and thereafter optionally salifying or esterifying the free carboxylic acid so formed, or
e) thereafter optionally converting the salt so formed into a free carboxylic acid, an ester or another salt.
[0045] The ring closure is normally brought about by heating the compound of the formula (VII) in an inert solvent; for example temperatures of 90-120°C and more suitably 100-110°C may be employed in a solvent such as toluene or the like. The reaction is best carried out under dry conditions under an inert gas.
[0046] The ester of the compound (II) produced may be isolated by any standard method such as fractional crystal - lisation or chromatography. We have found that it is most convenient to separate the desired product by column chromatography.
[0047] Any convenient ester may be used in the process of this invention. Since it is frequently desirable to form a salt of compounds (II), the ester employed is preferably one which is readily converted to the parent acid or its salt by mild methods of hydrogenolysis. In a further aspect therefore the invention includes a process for preparing a salt or free acid of a compound (II) which process comprises de-esterifying an ester of a compound of formula (II). Particularly suitable esters for use in this process include benzyl esters, optionally substituted in the para position by a lower alkoxy, or nitro group or a halogen atom.
[0050] Suitable methods include hydrogenation in the presence of a transition metal catalyst. The pressure of hydrogen used in the reaction may be low, medium or high but in general an approximately atmospheric or slightly superatmospheric pressure of hydrogen is preferred. The transition metal catalyst employed is preferably palladium on charcoal or on calcium carbonate. The hydrogenation maybe effected in a suitable solvent in which the ester is soluble such as aqueous dioxan or the like. If this hydrogenation is carried out in the presence of a base then a salt of compounds (II) is produced. Suitable bases for inclusion include NaHC03, KHC03, Na2C03, K2CO3, CaC03, MgCO3, LiHCO3, NH4OCOCH3 and the like. If no base is present then hydrogenation leads to the preparation of an acid within formula (II) which may then be neutralised if desired to yield a salt. Suitable bases which may be used to neutralise acids within formula (II) include LiOH, NaOH, NaHCO3, KOH, Ca(OH)2 and Ba(OH)2.
[0051] The salts of acids (II) may be converted to esters in conventional manner, for example by reaction with a reactive halide such as bromophthalide in solution in dimethylformamide or like solvent.
[0052] The substituent group or groups within the group R2 in the compounds of formula (II) may be varied by conventional reactions. Thus for example when a substituent is a nitro group it may be reduced in a conventional manner to an amino group, for example by catalysed hydrogenation. Similarly an amino group may be acylated to give a substituted amido group, for example by treatment with an acyl halide in the presence of an organic base. Substituents NHC02R3 where R3 is a benzyl group substituted as hereinbefore described may be converted to amino groups, for example by hydrogenolysis.
[0053] Compounds of the formula (II) wherein the group R2 contains one or more substituents CO2R10 as hereinbefore defined are preferably prepared from corresponding compounds of the formula (VII) wherein R2 contains corresponding substituents C02R31 where CO2R31 is a group readily convertible to a group CO2R10 by hydrogenolysis. Suitable and preferred hydrogenolysis methods and esters therefor are those so described hereinbefore for the de-esterification of CO2R1 ester groups.
[0054] The compound of the formula (VII) may be prepared by the reaction of a corresponding compound of the formula (VIII):
wherein R4, R5 and R6 are as defined in relation to formula (VII) with a diloweralkylphosphorochloridate and a triloweralkylamine followed by reaction with a derivative of the formula (IX):
where L0 is a sodium or thallium (I) cation or an ammonium ion substituted by up to three organic groups, and R2 is as defined in relation to formula (II).
[0055] When L0 is a substituted ammonium ion, it is preferably a tertiary ammonium ion, such as the triethylammonium ion. It is conveniently generated in situ by the reaction of a compound of the formula HSR2 with an amine, preferably a tertiary amine.
[0059] The reaction is generally carried out in an inert organic solvent such as tetrahydrofuran at a non-extreme temperature such as 0 to 40°C, for example 15-25°C.
[0060] The compound of the formula (VIII) may be prepared by the reaction of the compound of the formula (X):
wherein R41, R4, R5 and R6 are as defined in relation to formula (VIII) with ozone in the presence of trifluoroacetic acid followed by m-chloroperbenzoic acid.
[0061] The ozonolysis is generally performed at a depressed temperature such as -40 to -80°C, for example about -70°C and in solution in an inert solvent such as methylene chloride. Excess ozone is removed by flushing with an inert gas and thereafter a solution of the peracid is added to the reaction mixture.
[0062] The compound of the formula (X) may be prepared from the corresponding compound of the formula (XI):
wherein R41 is as defined in relation to formula (X) with a phosphine of the formula (XII):
where R4, R5 and R6 are as defined in relation to formula (X).
[0063] This reaction is normally effected in the presence of at least one equivalent of a base of relatively low nucleophilicity such as 2,6-lutidine at an ambient temperature in a dry solvent such as dioxan, tetrahydrofuran or the like.
[0064] The compound of the formula (XI) may be prepared from the corresponding carbinol of the formula (XIII):
wherein R41 is as defined in relation to formula (XI) by reaction with thionyl chloride.
[0065] This reaction is also normally effected in the presence of at least one equivalent of a base of relatively low nucleophilicity in a dry solvent such as dioxan or tetrahydrofuran but in this instance the reaction is performed at a depressed temperature, for example -30 to -10°C.
[0066] The preceding carbinol may be prepared by the reaction of a compound of the formula (XIV):
with a glyoxylic acid ester of the formula (XV):
wherein R41 is as defined in relation to formula (VII).
[0067] Normally this reaction is carried out in an inert solvent at an elevated temperature, for example in dry benzene under reflux.
[0069] The present invention provides the compounds of the formulae (VII) and (VIII), as useful intermediates. The process for the preparation of these compounds also forms part of this invention.
[0070] The present invention also provides a pharmaceutical composition which comprises a compound of the formula (II) as hereinbefore defined and a pharmaceutically acceptable carrier.
[0071] The composition of the invention includes those in a form adapted for oral, topical or parenteral use and may be used for the treatment of bacterial infection in domestic animals or humans.
[0072] Suitable forms of the compositions of this invention include tablets, capsules, creams, syrups, suspensions, solutions, reconstitutable powders and sterile forms suitable for injection or infusion. Such compositions may contain conventional pharmaceutically acceptable materials such as diluents, binders, colours, flavours, preservatives, disintegrants and the like in accordance with conventional pharmaceutical practice in the manner well understood by those skilled in the art of formulating antibacterial agents.
[0073] Preferably the compound of the formula (II) present in such compositions will be in-vivo hydrolysable to the parent acid or its salt.
[0074] The composition of this invention may beneficially also comprise a penicillin or cephalosporin. Certain particularly suitable penicillins for use in these compositions include amoxycillin trihydrate and sodium amoxycillin.
[0075] The present invention also provides a method of treatment and/or prophylaxis of bacterial infections in human beings or domestic animals, which method comprises the administration to the sufferer of an effective amount of a compound of the formula (II).
[0076] 'The following Examples illustrate this invention. The following Descriptions relate to the preparation of useful intermediates.
DESCRIPTION 1
4-Allyl-1-(1'-tert-butyloxycarbonyl-1'-triphenylphosphor- anylidenemethyl)azetidine-2-one
(i) Preparation of 4-allyl azetidin-2-one
[0077]
1,4 Pentadiene(d1) (30g) and chlorosulphonyl isocyanate (d2)(35.4 ml) were mixed and allowed to stand at room temperature for 3 days, in a pressure bottle. The thick, dark syrup obtained was diluted with methylene chloride (500ml) and added dropwise to a stirred solution of sodium sulphite (66g) in water (240ml).
[0078] The pH was maintained between 6.5 and 7.5 by the addition of 10% aqueous potassium hydroxide (600ml in total). The lower organic phase was separated and the aqueous phase extracted (x 2) with ethyl acetate. The combined organic extracts were dried over magnesium sulphate, filtered, and evaporated to give the crude azetidinone (d3) as a red oil (16.05g). This was sufficiently pure for use in subsequent reactions e.g. Description 1 (ii), but could be further purified by distillation b.p. 76-80°/ 0.2 mm.ν max (CHCl3) 3490, 1770 (strong), 1650 (weak)cm-1. δ ppm (CDC13) 2.39 (2H, t, J 6Hz, CH2) , 2.61 (1H, ddd, J 14Hz, 2Hz, 1.5Hz, collapsing with D20 to dd, J 14Hz, 2Hz, C3-H), 3.10 (1H, ddd, J 14Hz, 5Hz, 2Hz, collapsing with D20 to dd, J 14Hz, 5Hz, C3-H), 3.55-3.91 (1H, m, C4-H), 4.98-6.21.(3H, complex pattern, CH=CH2), 6.67 (1H, broad s, exch. D20) (Found: M, 111.0683. C6H9NO requires M, 111.0684).
(ii) Preparation of 4-allyl-1-(1'-hydroxy-1'tert-buty- loxycarbonylmethyl)azetidin-2-one
[0079]
tert-Butyl glyoxylate hydrate (6.22g) in benzene (120ml) was refluxed for 1 hour in a Dean-Stark apparatus to remove the water. The azetidinone (d3)(2.31g) was then added and the reaction mixture refluxed for 4 hours. Chromatography of the crude product as in Description 3(i) gave the alcohol (d4) as a pale yellow oil (4.48g). ν max (CHCH3) 3490, 1755, 1735, 1640 (weak) cm-1 δ ppm (CDC13) 1.50 (9H, s, But), 2.20-3.25 [4H, 2.66 (1H, dd, J 3Hz, 14Hz, C3-H), and 3.09 (1H, dd, J 14Hz, 5Hz, C3-H) obscuring 2H, CH2] ; 3.68-4.10 (1H, m, C4-H), 4.47 (1H, broad s, exch. D2O, OH); 4.98 - 5.37 (3H, m, sharpening with D20), 5.52 - 6.23 (1H, m, CH=CH2). M+ at m/e 241 and (m/e +1).
(iii) Preparation of 4-allyl-1-(1'-tert-butyloxycarbonyl-1'-triphenylphosporanylidenemethyl)azetidin-2-one
[0081] A stirred solution of the alcohol (d4) (4.2g) in dry tet- rahydrofuran (120ml) under argon, was cooled to -20°, and treated with lutidine (4.03ml) in tetrahydrofuran (15ml; Thionyl chloride (2.54ml) in tetrahydrofuran (15ml) was added dropwise. After allowing to reach 0° over 30 minutes, the solution was filtered, the lutidine hydrochloride being washed with toluene.
[0082] The combined filtrate and washings were evaporated to dryness. The residue was taken up in dry dioxan (100ml) and treated with lutidine (4.03ml) and triphenylphosphine (9.1g). After stirring at room temperature overnight, the phosphorane (d5) was isolated as in Description 3 (ii) and obtained as white crystals (4.62g) from ether mp. 188-9°, ν max (CHCl3) 1730, 1638, 1610cm-1 (Found: C, 74.1; H, 6.8; N, 3.0, P, 6.2% C30H32N03P requires C, 74.2, H, 6.6, N, 2.9, P, 6.4%).
DESCRIPTION 2
4-Allyl-1-(1'-methoxycarbonyl-1'-triphenylphosphoranylid- enemethyl)azetidin-2-one
(i) Preparation of 4-allyl-1-(1'-hydroxy-1'-methoxycarbonyl- methvl)azetidin-2-one
[0084] Methyl glyoxylate hydrate (9.75g) in benzene (500ml) was refluxed for 1 hour in a Dean-Stark apparatus to remove the water. The azetidinone (d3) (2.68g) was then added and the reaction mixture refluxed for 2 hours. A further portion of the azetidinone (1.34g) (d3) was then introduced, and refluxing continued for 3 hours. Chromatography of the crude product as in description 3 (i) gave the alcohol (d6) as a pale yellow oil (5.33g). ν max (CHCl3) 3500, 3350 (broad), 1760-1740 (strong), 1640 (weak)cm-1. δppm (CDC13) 2.24-2.90 (3H, m, including [1H, dd, J 3Hz, 14.5 Hz at δ 2.63]), 3.11 (1H, dd, J 4.5Hz, 14.5Hz), 3.72 - 4.42 (5H, including [3H, s, at δ 3.90], 1H, exch. D20), 5.00-6.29 (4H, m including [1H, s, at δ 5.48]).
(ii) Preparation of 4-allyl-1-(1'-methoxycarbonyl-1'-tri- phenylphosphoranylidene-methyl)azetidin-2-one
[0085]
A stirred solution of the alcohol (d6) (5.23g) in dry tetrahydrofuran (150ml) under argon, was cooled to -20°, and treated with lutidine (6.06 ml) in tetrahydrofuran (20ml). Thionyl chloride (3.83ml) in tetrahydrofuran (20ml) was added dropwise. After allowing to reach 0° over 20 minutes, the solution was filtered, the lutidine hydrochloride being washed with toluene.
[0086] The combined filtrate and washings were evaporated to dryness. The residue was taken up in dry dioxan.(150ml) and treated with lutidine (6.06ml) and triphenylphosphine (13.7g). After stirring at room temperature, overnight, the phosphorane (d7) was isolated as in Description 3 (ii) and obtained as white crystals (7.3g) from ether m.p. 208-212°. ν max (CHC13) 1738, 1640, 1620 cm-1 (Found: C, 72.6; H, 5.9; N, 3.0%. C27H26NO3P requires C, 73.1; H, 5.9; N, 3.2%).
- DESCRIPTION 3
(i) 4-Allyl-1-(1'-benzyloxycarbonyl-1'-triphenylphosphoranylid- enemethyl)azetidin-2-one
[0088] Benzyl glyoxylate hydrate (6g) in benzene (120ml) was refluxed for 0.5 hours in a Dean-Stark apparatus to remove the water. The azetidinone (d3) (2.13g) was added and the reaction mixture refluxed for 4 hours. The solution was cooled, evaporated, and chrcmatographed on silica gel, eluting with ethyl acetate-petroleum ether mixtures to give a colourless oil (5.6g) consisting mainly of the isomers of (d8) and sufficiently pure for use in subsequent reactions. Rechromatography of a small portion of this oil, eluting with chloroform gave (d8) as an oil. ν max (CHC13) 3420, 1750 (strong), 1640 (weak)cm-1. δ ppm (CDCl3) 1.90-3.05 [4H, m, including S 2.53 (1H, dd, J 15Hz, 2Hz, C3-H), 2.92 (1H, dd, J, 15Hz, 5Hz, C3-H), obscuring 2H, CH2], 4.52 (1H, broad s, exch. D20, -OH), 4.85-5.90 [6H, m, including δ 5.40 (1H, broad, collapsing with D20 to singlet, H-C-OH) + complex pattern for CH2Ph and CH=CH2], 7.29 (5H, s).
(ii) Preparation of 4-allyl-1-(1'-benzyloxycarbonyl-1'-triphenylphosphoranylidenemethyl)azetidin-2- one.
[0090] A stirred solution of the alcohol (d8) (6.6g) in dry tetrahydrofuran (200ml), under argon, was cooled to -20°, and treated with lutidine (5.13g) in tetrahydrofuran (10ml). Thionyl chloride (5.70g) in tetrahydrofuran (20ml) was added dropwise. After allowing to reach 0°C over 20 minutes, the precipitated solid was filtered off, washing with dry toluene.
[0091] The combined filtrate and washings were evaporated to dryness and the residue taken up in dry toluene, filtered and evaporated. The gum obtained was taken up in dioxan (200ml) and treated with triphenylphosphine (12.6g) and lutidine (5.53ml). After stirring under argon at room temperature for 3 hours and standing overnight, the precipitated solid was filtered off. The filtrate was evaporated to dryness. Chromatography on silica gel eluting with ethyl acetate-petroleum ether mixtures, gave the required phosphorane, initially as a foam, which crystallised from ether (5.7g) m.p. 150-6°C. ν max (CHC13) 1730, 1638, 1610 cm -1.
DESCRIPTION 4
4-Allyl-1-(1'-p-nitrobenzyloxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)azetidin-2-one.
(i) Preparation of allyl-1-(1'-hydroxy-1'-p-nitrobenzyloxycarbonylmethyl)azetidin-2-one
[0092]
p-Nitrobenzylglyoxylate hydrate (6.8g) in benzene (120ml) was refluxed for one hour with removal of water (Dean-Stark). The azetidinone (d3) (3g) was added and the mixture refluxed for two hours. The solution was cooled, the solvent was evaporated, and the residue was chromatographed. Elution with 80% ethyl acetate/petroleum ether (60-80°C) gave the product. The product was rechromatographed to complete purification and collected as an oil (3.2g) (37%)ν max (CHCl3) 3,500 (OH) , 1755 (br), 1530, 1355cm-1 . δ ppm (CDC13) 2.39 (2H, m CH2CH=CH2), 2.61 (1H, dd, J 16H, 4Hz, C3-H), 3.05 (1H, dd, J 16Hz, 6Hz, C3-H), 3.92 (1H, m, C4-H), 4.63 (1H, m, collapsing to a singlet on D20 exchange, CH-OH), 4.80 to 5.80 (6H, complex pattern including CH2PhNO2 at 5.35, OH [exchangeable] and CH=CH2) 7.56 and 8.23 (4H, ABq, J 8Hz, aromatics).
(ii) Preparation of 4-allyl-1-(1'-p-nitrobenzyloxycarbonyl-1'-triphenylphosphoranylidenemethyl) azetidin-2-one
[0094] A stirred solution of the alcohol (d10) (1.6g) in dry THF (100ml) was treated with 2,6-lutidine (1.07g) and thionyl chloride (1.19g) in THF (20ml) at -20°, and stirring was continued for 20 minutes. The mixture was filtered, the solvent was evaporated, and the residue was azeotroped twice with toluene. It was dissolved in dioxan (100ml), and 2,6-lutidine (1.07g) and triphenylphosphine (2.62g) were added. The reaction was stirred overnight at RT and filtered. The solvent was evaporated, and the residue was chromatographed. After decolourising with charcoal (ethanol/ethyl acetate) and trituration of the residue from the evaporated solution with ether, (d11) was obtained as a yellow solid (1.5g; 53%) m.p. 182-3° ν max (CHC13) 1740, 1620, 1525, 1355cm-1. (Found: C, 70.26; H, 5.33; N, 4.80. C33H29N2O5P requires C, 70.21; H, 5.14; N, 4.96%).
DECSCRIPTION 5
4-Allyl-1-(1'pivaloyloxymethoxycarbonyl-1'triphenyl- phosphoranylidenemethyl)azetidine-2-one
[0096] 4-Allylazetidin-2-one(d3) (2.0 g) and glyoxylic acid monohydrate (1.75 g) were stirred together in dry dimethylformamide (10 ml) for 6 hours in the presence of 4A molecular sieves. The mixture was then cooled in an ice bath and powdered potassium carbonate (1.31 g) was added. It was allowed to warm to room temperature and stirred for 5 minutes prior to adding pivaloyloxymethyl bromide (5.3 g). The reaction was stirred overnight and then poured into a mixture of N/10 hydrochloric acid (80 ml) and ethyl acetate (80 ml). The organic phase was separated and the aqueous solution washed with further ethyl acetate (50 ml). The ethyl acetate solutions were combined, washed with saturated aqueous sodium bicarbonate, then brine and dried over sodium sulphate. It was concentrated in vacuo to'give the crude ester (d 13) as a yellow oil (4.7 g) .
[0097] The crude ester (d 13) (4.7 g) was dissolved in ary tetrahydrofuran (80 ml) and stirred at -20° under argon It was treated with 2,6-lutidine (3.7 ml) followed over a period of 5 minutes by a solution of thionyl chloride (2.3 ml) in tetrahydrofuran (20 ml). The reaction was allowed to warm to ambient temperature over a period of ½ hour and then filtered. The solid was washed with dry toluene and the combined filtrates concentrated under reduced pressure. The vestigial thionyl chloride was removed by two further evaporations from toluene to give the chloride (d14) as a brown oil.
[0098] The chloride (d 14) was dissolved in dry dioxane (80 ml) and treated with triphenylphosphine (8.2 g) and 2,6-lutidine (3.7 ml). The reaction mixture was stirred overnight and then filtered; the filtrate concentrated and re-dissolved in ethyl acetate (100 ml). This solution was washed free of base with N/10 hydrochloric acid (ca 100 ml) and then washed with brine and dried over sodium sulphate. The solution was concentrated and then chromatographed on silica gel 60 (<230 mesh) eluting with ethyl acetate/60-80° petroleum ether 7:3 to give a foam. This was dissolved in diethyl ether (20 ml) and a white solid rapidly crystallised out. This was 4-allyl-1-(1'-pivaloyloxymethoxycarbonyl-1'-triphenylphosphoranyl- idenemethyl)azetidine-2-one (d 15) which was obtained in a yield of 3.06 g; m.p. 140-1420 (ethyl acetate/60-80a petroleum ether; ν max (CHC13) 2980, 1740 and 1635 cm-1.
EXAMPLE 1
t-Butyl 7-oxo-3-p-nitrophenylthio-1-azabicyclo-[3.2.0]-hept-2-ene-2-carboxylate
(a) Preparation of 1-(1'-t-butoxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-carboxymethylazetidin-2-one
[0101] (2g) was dissolved in dry methylene chloride (100ml) and treated with trifluoroacetic acid (3.2ml). The solution was cooled to -70°C and ozonised until the solution turned - blue. Excess ozone was removed by passing through argon and m-chloroperbenzoic acid (720 mg) in methylene chloride (20ml) was added. The mixture was allowed to reach RT and stirred overnight. The solvent was evaporated and the residue chromatographed on Merck Kieselgel 60 (<230 mesh). Elution with 50% ethanol/ethyl acetate gave the phosphorane-acid (2a) as a colourless foam which crystallised from ethyl acetate/ether (1.6g) as a mixture of zwitterion and trifluoroacetic acid salt, ν max 1770, 1750, 1670, 1590cm-1.
[0102] The product (1.6g) was taken up in CHCl3 (50ml) and stirred with basic alumina (4g) overnight. The solution was filtered, the solvent evaporated and the residue triturated with ether to yield the phosphorane-acid (2a) as a white solid (0.9g) mp 141-3°C. νmax (CHCl2) 1750, 1595, 1590cm-1.
[0103] The acid (2a) was further characterised by treatment with benzyl bromide and potassium carbonate in dimethylformamida: to give the benzyl ester (2b), obtained as white crystals (ex ether) m.p. 176.5-178°C.ν max (CHCl3) 1735, 1640, 1610 cm-1. (Found: C, 72.20; H, 6.59; N, 2.28; C36H36NO5P re- quires C, 72.83; H, 6.11; N, 2.36%).
(b) Preparation of 1-(1'-t-butoxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-(p-nitrophenylthiocarbon- ylmethyl)azetidin-2-one
[0105] The acid (2a) (1.06g; 2mmol ) and Et3N (222mg; 2.2mmole) were stirred in dry THF .(20ml) at RT. A solution of diethyl phosphorochloridate (363 mg; 2.2mmol) in THF (5ml) was added dropwise under argon at RT and the mixture stirred for 3h. The solution was filtered and to the filtrate was added (787mg; 2.2 mmol) of thallium (I) p-nitrophenyl- thiolate. The mixture was stirred overnight, filtered and the filtrate evaporated. Chromatography on Merck Kieselgel 60 (< 230 mesh) using ethyl acetate - petrol yielded the product (3) as an oil which crystallised from ethyl acetate/petrol as a light yellow crystalline solid (570 mg; 56% mp 115-6°C. ν max (CHCl3) 1740, 1720 (sh), 1640cm-1 (Found: C, 65.82; H, 5.40; N, 4.32. C35H33N2O6SP requires C, 65.62; H, 5.16; N, 4.38%).
(c) Preparation of t-butyl 7-oxo-3-p-nitrophenylthio-1-azabicyclo-[3.2.0]hept-2-ene-2-carboxylate
[0107] The phosphorane (3) (128mg) was heated in refluxing toluene (50ml) for 15 min. The solvent was evaporated and the residue chromatographed on Merck Kieselgel 60 (<230 mesh) to yield 15 mg of crude product. Re-chromatography yielded the title product (4) as a light yellow crystalline solid from ethyl acetate/petrol mp 148-50°C ν max (CHCl3) 1790, 1710, 1695, 1525, 1345cm-1. δ ppm (CDCl3) 1.57 (9H, s, Co2C(CH3)3), 2.70 (2H, d, J 9.5Hz, C4-CH2), 2.83 (1H, dd, J 17, 3Hz, C6-H trans), 3.43 (1H, dd, J 17, 5Hz, C6-H, cis), 4.12 (1H, m, C5-H), 7.62 and 8.17 (4H, ABq, J 9Hz aromatic protons), λmax (EtOH) 265 nm (ε = 14,300) 309 nm (ε = 17,300), 346 nm (sh) (ε = 13,700).
EXAMPLE 2
t-Butyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate.
(a) Preparation of 1(1'-butoxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-(phenylthiocarbonyl- methyl)azetidin-2-ene
[0109] The acid (2a) (754mg; 1.5 mmol) was dissolved in dry THF (15ml) containing Et3N (167mg; 1.6 mmol) and stirred at RT. A solution of diethylphosphorochloridate (272mg; 1.6mmol) in THF (5ml) was added dropwise to the solution under argon. Stirring was continued for 3h. The solution was filtered, and to the solution was added thallium (I) phenylthiolate (500mg; 1.6 mmol). Stiring was continued overnight. The solution was filtered, he solvent evaporated and the residue chromatographed on Merck Kieselgel 60 using ethyl acetate-petrol to yield the phosphorane (5) (700mg) as an oil. Trituration with ether gave the phosphorane as a microcrystalline solid (55 mg) mp 152-5°C. νmax 1740, 1700, 1640cm-1 (Found: C, 70.74; H. 5.76; N, 2.43. C35H34NO4SP requires C, 70.59; H, 5.71; 2.35%).
(b) Preparation of t butyl-7-oxo-3-phenylthio-1-azabi- cyclo-[3.2.0]hept-2-ene-2-carboxylate
[0111] The phosphorane (5) (120mg) was refluxed in dry toluene (10ml) under argon for six hours. The solvent was evaporated and the product chromatographed on Merck Kieselgel 60 to yield the title product (6) as the second compound eluted from the column (25mg; 39%). max (CHCl3) 1785, 1700cm-1. δ ppm (CDCl3) 1.56 (9H, s, CO2C(CH3)3); 2.57 (2H, d, J 9Hz; C4-CH2); 2.74 (1H, dd, J. 17, 3Hz, C6-H, trans), 3.32 (1H, dd, J 17, 5Hz, C6-H, cis), 3.97 (1H, m. C5-H), 7.39 (5H, m, Ph),λmax (EtOH) 313 nm (∈ = 9,510) (Found: M, 317.1105,C17H19NO3S requires 317.1085).
EXAMPLE 3
Methyl -7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate.
(a) Preparation of 1=(1'-methoxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-carboxymethylazetidine-2-one
[0114] (4.47g) in dry methylene chloride (250ml), was treated with trifluoroacetic acid (7.7ml). The solution, cooled to -70°C, was ozonised until it became blue. After passing argon through to remove excess ozone, m-chloroperbenzoic acid (1.74g) in methylene chloride (50ml) was added. The stirred mixture was allowed to reach room tempreature, and after stirring overnight, was evaporated to dryness. After re-evaporation from dry toluene the residue was chromatographed on Merck Kieselgel 60. Elution with ethyl acetate gave m-chlorobenzoic acid. Further elution with 10% ethanol acetate gave the phosphorane-acid (8a), partially as the trifluoroacetic acid salt, as a yellow foam (2.7g), νmax (CH2Cl2)1770, 1755, 1738, 1705-1675 (several weak peaks), 1585cm-1.
[0115] This foam was taken up in dry methylene chloride (70ml), and stirred with basic alumina (8g), for 2 hours.
[0116] Evaporation of the filtered solution gave a foam (3g). Trituration with ether gave the zwitterionic form of the acid-phosphorane (8a), as a pale yellow solid, which was collected and dried in vacuo (2.35g) ν max (CH2Cl2) 1750, 1740, 1590cm-1.
[0117] The acid (8a) was characterised by treatment with benzyl bromide and potassium carbonate in dimethylformamide to give the benzyl ester (8b), as white crystals (ex ethyl acetate/petroleum ether), mp 146-8°C,νmax (CHCl3) 1740, 1620cm-1 (Found: C, 71.71; H, 5.67; N, 2.44. C33H30NO5P requires C, 71.87; H, 5.44: N, 2.54%.
(b) Preparation of 1-(1'-methoxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-(phenylthiocarbonyl- methyl)azetidin-2-one
[0119] The acid (8a) (461mg; 1 mmol) was dissolved in dry THF containing Et3N (110mg; 1.1 mmol) and stirred at RT whilst a solution of diethylphosphorochloridate (152ng; 1.1 mmol) in THF (5ml) was added dropwise at RT under argon. The solution was filtered, and thallium (I) phenylthiolate (345 mg; 1.1 mmol) was added to the filtrate. Stirring was continued overnight, the solution filtered, the solvent evaporated and the residue chromatographed to yield the phosphorane (9)as an oil (400mg) . Trituration with ether yielded the phosphorane as a microcrystalline solid mp
[0120] 172-3°C,νmax 1740, 1700, 1620cm-1 (Found: C, 68.84; H, 5.24; N, 2.33. C32H28NO4SP requires C, 69.43; H, 5.06; N, 2.53%).
(c) Preparation of methyl 7-oxo-3-phenylthio-1-aza- bicyclo[3.2.0]hept-2-ene-2-carboxylate
[0122] The phosphorane (9) (80mg) was heated under reflux in dry toluene (5ml) for five hours. The solvent was evaporated and the product chromatographed to yield the title compound (10) (9.8mg,25%),ν max (CHCl3) 1790, 1705cm-1. δ ppm (CDCl3) 2.57 (2H, d, J 9Hz; C4-CH2) 2.76 (1H, dd, J 17Hz, 3Hz, C6-H, trans), 3.34 (1H, dd, J 17Hz, 5Hz, C6-H, cis), 3.82 (3H, s, C02CH3), 4.00 (1H, m, C5-H), 7.35 (5H, m, Ph), λmax (EtOH) 313 nm (∈ = 11,400). (Found: M, 275.0616, C14H13NO3S requires 275.0616).
EXAMPLE 4
Benzyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
(a) Preparation of 1-(1'-Benzyloxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-carboxymethylazetidin-2-one
[0125] (2.076g) in dry methylene chloride (120ml) was treated with trifluoroacetic acid (3.08ml). The solution, cooled to -70°C, was ozonised until it became blue. After passing argon through to remove excess ozone, m-chloroperbenzoic (0.69g) in methylene-chloride (25ml) was added. The stirred mixture was allowed to reach room temperature. After stirring for 3 days, work up and chromatography as in Example 1 , gave the phosphorane . acid (12) partially as the trifluoroacetic acid salt, as a yellow foam (1.215g),νmax (CHCl3) 1770 (shoulder) 1750, 1730, 1700, 1665, 1590, 1575cm-1,
[0126] This foam was taken up in chloroform (20ml) and stirred with basic alumina (4g) for 4 hours. Evaporation of the filtered solution gave the zwitterionic form of the acid-phosphorane (12) as a foam (0.855g)νmax (CHCl3) 1735, 1590, 1585, 1575cm-1.
(b) Preparation of 1(1'-benzyloxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-(phenylthiocarbonylmethyl) azetidin-2-one.
[0128] The acid (12) (1.07g; 2 mmol) and Et3N (220mg; 2.2 mmol) in dry THF (30ml) were stirred at RT and a solution of diethyl phosphorochloridate (380mg; 2.2 mmol) in THF (5ml) was added dropwise under argon and stirred for three hours at RT. To the solution was added thallium (I) phenylthiolate (686mg; 2.2 Mmol) and the mixture stirred overnight. The solution was filtered and the solvent evaporated to yield an oil. Chromatography on Merck Kieselgel 60 using ethyl acetate/petrol by gradient elution gave the title product (13), which crystallised from ethyl acetate/ether as a microcrystalline solid mp 160-1°C,νmax 1745, 1705, 1620cm-1 (Found: C, 72.12; H, 5.28,; N, 2.15. C38H32NO4SP requires C, 72.50; H, 5.09; N, 2.23%).
(c) Preparation of benzyl 7-oxo-3-phenylthio-1-aza- bicyclo[3.2.0]hept-2-ene-2-carboxylate
[0130] The phosphorane (13) (150mg) was refluxed in dry toluene (100ml) under argon for nine hours. The solvent was evaporated and the product chromatographed on Merck Kieselgel 60 using ethyl acetate/petol as eluant to yield the title compound (14) as the major product (25 mg; 30%),ν max (CHC13) 1790, 1705 cm-1. δ ppm ((CD3)2C0) 2.72 (2H, s, C4-CH2), 2.87 (1H, dd, J 17, 3Hz, C6-H, trans), 3.32 (1H, dd, J 17, 5½Hz, C6-H, cis), 4.05 (1H, m, C5-H), 5.23 (2H, s, CO2CH2Ph), 7.20-7.70 (10H, m, SPh and CO2CH2Ph), λmax (EtOH) 317 nm (∈ = 12,250). (Found: M, 351.0929, C20H17NO3S requires 351.0929).
EXAMPLE
p-Nitrobenzyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
(a) Preparation of 1-(1'-p-Nitrobenzyloxycarbonyl-1'-triphenylphosphoranylidenemethyl)-4-carboxymethyl- azetidin-2-one
[0132] The phosphorane (15, prepared as in Description. 4) (2.82g) in dry methylene chloride (125ml) was treated with trifluoroacetic acid (4ml) at 0°. The solution was cooled to -70° and treated with ozone until blue. Argon was passed through to remove excess ozone, and m-chloroperbenzoic acid (0.9g) in methylene chloride (20ml) was. added, and the mixture was stirred at RT overnight. The. solvent was evaporated, and the resulting white solid was dissolved in ethyl acetate and chromatographed on silica gel. Elution with 10% ethanol/ethyl acetate gave the product as the trifluoroacetic acid salt. The product was stirred in ethyl acetate with basic alumina (6g) for two hours. Evaporation of the solvent and trituration of the residue with diethyl ether gave the acid (16) as a light yellow hygroscopic solid (2g; 69%) solid. A small portion crystallised from diethyl ether gave a microcrystalline solid m.p. 127-33°C.νmax (CHCl3) 1745, 1600, 1355, 1115cm-1. (Found: C, 64.59; H, 4.82; N, 4.66. C32H27N207P. ½H2O requires C, 64.97; H, 4.73; N, 4.73).
(b) , Preparation of 1-(1'-p-nitrobenzyloxycarbonyl-1'-triphenylphosphoranylidenemethyl)-4-(phenylthio- carbonvl)azetidin-2-one
[0134] The acid (16) (1.16g) and Et3N (220mg) in dry THF (30ml) were stirred at RT, and a solution of diethyl phosphorochloridate (380mg) in THF (5ml) was added dropwise under argon and stirred at RT for three hours. To the solution was added thallium (I) phenylthiolate (686mg), and the mixture was stirred overnight. The solution was filtered', and the solvent was evaporated. Chromatography yielded the phosphorane thioester (17) as a light tan solid from diethyl ether/ethyl acetate (950mg; 70%). Recrystallisation from ethyl acetate gave a white solid m.p. 186-8°C. νmax (CHC13) 1745, 1705, 1615, 1350, 1145cm-1. (Found: C, 67.40; H, 4.68; N, 4.02. C38H31N2O6PS requires C, 67.66; H, 4.60; N, 4.15%).
(ii) Alternative Procedure
[0135] The acid, (16, prepared as in (a) above)(2.90g) and Et3N (550mg) in dry THF (75ml) were stirred at RT and a solution of diethyl
added dropwise under argon and stirred for three hours at RT. Thiophenol (550mg) was added to the solution followed by Et3N (550mg) and the mixture stirred at RT. for two hours. The solvent was evaporated and the residue chromatographed to yield the thioester-phosphorane as a light tan solid from ethyl acetate/ether. Recrystallisation from ethyl acetate gave a white solid, shown by m.p., - i.r. and analysis to be identical with (17) as in b (i) above.
(c) Preparation of p-nitrobenzyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
[0137] The phosphorane (17) (550mg) was refluxed in dry toluene (500ml) for 24 hours with removal of water (Dean-Stark) under argon. The solvent was evaporated and the product chromatographed on florisil (200-300 U.S. mesh) using ethyl acetate/petrol (60-80°) as eluant to yield the title compound (52mg; 18%) as a crystalline solid from benzene/petrol (60-80°C) mp 112-4°C.νmax (CHC13) 1790, 1705 cm-1. δ ppm (CDCl3) 2.63 (2H, d, J 9Hz, C4-CH2), 2.81 (1H, dd, J17, 3Hz, C6-H trans), 3.38 (1H, dd, J17, 51Hz, C6-H, cis), 4.04 (1H, m, C5-H), 5.26 and 5.49(2H,ABq J14Hz, benzylic CH2), 7.36 (5H, m, SPh),7.60 (d,2H,
8.15(d,2H,J9Hz,PhNO2)λmax(EtOH)266 nm (∈10,200),317nm(∈8,900) (Found: C, 60.56; H, 3.93; N, 6.91% C20H16N2O5S requires C, 60.61; H, 4.04; N, 7.07%).
EXAMPLE 6
Benzyl 7-oxo-3-p-acetamidophenylthio-1-azabicyclo[3.2.0] hept-2-ene-2-carboxylate
(a) Preparation of 4-(p-Acetamidophenvlthiocarbonyl- methyl)-1(1'-benzyloxycarbonyl-1'-triphenylphos- phoranvlidenemethyl)azetidin-2-one
[0139] The acid (12; prepared as in Example 4a) (268mg) in dry tetrahydrofuran (10ml) under argon was treated with triethylamine (76mg), followed by diethylphosphorochloridate (130mg), diluted with tetrahydrofuran (5ml). After' stirring at room temperature for 3 hours, the solution was added to freshly prepared sodium p-acetamidophenythio- late in tetrahydrofuran [prepared by treating p-acetamido- phenylthiol (92mg) in dry tetrahydrofuran (5ml)/hexamethylphosphoramide (89mg), under argon, at 0°, with sodium hydride (26mg of a 50% suspension in oil)].
[0140] The stirred mixture was allowed to warm up from 0° to room temperature over 30 minutes, and after a further hour was diluted with ethyl acetate (60ml), washed with water, then brine, dried over magnesium sulphate and filtered and the filtrate was evaporated. Chromatography on Merck Kieselgel 60 (10g), eluting with ethyl acetate, gave the required thioester (19) as white crystals (128mg). Recrystallisation from chloroform/ethyl acetate gave white needles m.p. 181-3°C, νmax (Nujol) 1730, 1700, (broad), 1620, 1590cm-1. νmax (KBr) 1730, 1695 (broad), 1620, 1595cm-1. (Found: C, 69.81; H, 5.32; N, 4.35. C40H35N2SO5P requires C, 70.00; H, 5.10; N, 4.08%).
[0141] Note: This thioester (19) was also prepared substituting the sodium thiolate mixture by solid thallium (I)p-acet- amidophenylthiolate. A comparable yield was obtained.
(b) Preparation of Benzyl 7-oxo-3-p-acetamidophenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
[0143] The phosphorane (19) (136mg) was suspended in dry toluene (10ml) and the mixture was evaporated to dryness. The residue was suspended in dry toluene (60ml), and the mixture was degassed and heated, under argon, under reflux with a Dean-Stark head. After 5 hours the pale yellow solution was cooled to room temperature, and the solvent was evaporated. The residue was taken up in ethyl acetate (12ml), and-left overnight at 5°, when buff coloured crystals were obtained. These were collected (97.5mg) and shown by thin layer chromatography to be recovered starting material. The solution was evaporated, and the residue was chromatographed on Merck Keiselgel 60, eluting with ethyl acetate/petrol mixtures to give the required compound (20), initially as a gum (7.5mg) contam- .inated with triphenylphosphine oxide. Trituration of this gum with diethyl ether gave (20), as a white solid (4.2mg),νmax (CHCl3) 1782, 1700 (shoulder), 1695, 1590 cm-1. λmax (ethanol) 312 nm and 245 nm. δ ppm (CDCl3) 2.12 (s, 3H, CH3); 2.57 (2H, d, J 8Hz, C4-CH2), 2.74 (1H, dd, J 16Hz, 3Hz, C6-H); 3.32 (1H, dd, J 16Hz, 5Hz, C6-H); 4.00 (1H, m, C5-H); 5.27 (2H, s, CH2Ph); 7.12-7.62 (14H, Ar + Ph3P=0); 7.71 (1H, s, NH).
EXAMPLE 7
Benzyl 7-oxo-3-p-aminophenythio-1-azabicclo[3.2.0]hept-2-ene-2-carboxylate
(a) Preparation of 4-(p-Aminophenylthiocarbonylmethyl)-1(1'-benzyloxycarbonyl-1'-triphenylphosphoranylidene- methvl)azetidin-2-one
[0145] The acid (12, prepared as in Example 4a) (1.675g) in dry tetrahydrofuran (80ml), under argon, was treated with triethylamine (0.472g) and diethylphosphorochloridate (0.807g). After stirring at room temperature for 3 hours the reaction mixture was added to freshly prepared sodium p-amino-phenylthiolate in tetrahydrofuran [prepared by treating p-aminophenylthiol (0.428g) in dry tetrahydrofuran (30ml)/hexamethylphosphoramide (0.505g), under argon at 0°, with sodium hydride (0.165g of a 50% suspension in oil)].
[0146] The stirred mixture was allowed to warm from 0° to room temperature. After a total of 1.5 hours, work-up as in Example 6, followed by chromatography on Merck Keiselgel 60 (60g), eluting with from 50% ethyl acetate in petroleum other (60-80°C) to neat ethyl acetate gave the required thioester (21) as a cream coloured solid (0.9g). Recrystallisation of a portion from hot ethyl acetate/petroleum ether (60-80°) gave "spherical crystals" m.p. 114.5-118°, ν max (CHC13) 3330, 1738, 1685 (broad, weak), 1620, 1600 (shoulder)cm-1.
(b) Preparation of Benzyl 7-oxo-3-p-aminophenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
[0148] The phosphorane (21) (0.461g) was taken up in dry toluene, and the mixture was evaporated to dryness. The residue was suspended in dry toluene (250ml), and the mixture was degassed and heated to reflux. A pale yellow solution was obtained. After refluxing for 6.5 hours the solution was left in the refrigerator overnight. The toluene solution was decanted from some gummy material and evaporated to dryness. Trituration of the residue with dry diethyl ether gave recovered (21) as a solid (414mg). . The ethereal solution was evaporated to dryness and the residue was taken up in toluene and chromatographed on Merck Keiselgel · 60 (4g), eluting with mixtures of ethyl acetate and petroleum ether (60-80°C), to give the required bicyclic product (22) as a gum (3.5mg). νmax (CHC13) 3300 (weak), 1780 (strong), 1700, 1685, (weak), 1620, 1600cm-1. A max (ethanol) at 314 nm and 261.5 nm.
[0149] (Treatment of this p-aminophenylthio, compound (22) with triethylamine/acetyl chloride gave the p-acetamidophenylthio compound (20) as shown by thin layer chromatography).
Example 8
Preparation of Benzyl 7-oxo-3-p-aminophenylthio-1-azabicyclo [3.2.0]hept-2-ene-2-carboxylate (Alternative Procedure)
[0151] A catalyst of 10% palladium on charcoal (Engelhard 4505, 50mg) suspended in 90% aqueous ethanol (10ml) was pre- hydrogenated for 20 minutes at room temperature/atmospheric pressure. Benzyl 7-oxo-3-p-nitrophenylthio-1-azabicyclo [3.2.0]hept-2-ene-2-carboxylate (50mg) partially dissolved in ethanol (10ml) was added, and the mixture was hydrogenated at room temperature and atmospheric pressure for 1.5 hours. The catalyst was removed by filtration through "High-Flo", and the colourless filtrate was evaporated to give an oil (35mg) identical by TLC, u.v. and I.R. to the product (22) obtained in Example 7.
EXAMPLE 9
Benzyl 7-oxo-3-(4-p-nitrobenzyloxycarbonylaminophenylthio)- 1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
(a) Preparation of 1-(1'-Benzyloxycarbonyl-1-triphenyl- phosphoranylidenemethyl)-4-(p-nitrobenzyloxycarbon- ylaminophenylthiocarbonylmethyl)azetidin-2-one
[0153] The phosphorane (22) (438mg) in dry tetrahydrofuran (60ml), under argon was treated with powdered sodium hydroxide(27.2mg) and p-nitrobenzylchloroformate (147 mg). After stirring at room temperature for 1.5 hours, the solvent was removed by evaporation, and the residue was taken up in chloroform, washed with brine, dried over magnesium sulphate and filtered, and the filtrate was evaporated. Chromatography on Merck Keiselg el 60, eluting with from 50% ethyl acetate in petroleum ether (60-800) to neat ethyl acetate gave the required thioester (23) as a white solid (255mg), contaminated with a little starting material (22). Further elution with a mixture of chloroform/ ethyl acetate gave a further (109mg) of the required product (23). A portion was recrystallised from chloroform/ether. The crystals were dried in vacuo at 100°C for a total of 11 hours, to give fine white crystals m.p. 205-7°C (dec.) ν max (nujol) 1742, 1738, 1700, 1680 (weak), 1605, 1590, 1518, 1345cm-1. (Found: C, 65.52; H, 4.46; N, 4.86. C46H38N3O8SP.H2O requires:- C, 65.50; H, 4.75; N, 4.98%).
(b) Preparation of Benzyl 7-oxo-3-(4-p-nitrobenzyloxy- carbonylaminophenylthio)-1-azabicyclo[3.2.0] hept-2-ene-2-carboxylate
[0155] The phosphorane (23) (850mg) was suspended in dry toluene (500ml) and heated under an atmosphere of argon under reflux using a Dean-Stark apparatus to remove water. A clear, pale yellow solution was obtained. After refluxing for 6.5 hours the slightly darker solution was cooled and reduced by evaporation to about 150ml. On storing overnight at 5°, recovered starting material (551mg) was precipitated. The solution was evaporated, and the residue was chromatographed on florisil (200-300 U.S. mesh). Elution with 20-30% ethyl acetate in petroleum ether (60-80°C) gave the required bicyclic compound (24) contaminated with triphenylphosphine oxide and some non- bicyclic S-lactam containing material as a gum (37.5mg). Trituration of this gum with diethyl ether gave a white solid (14.8mg). This solid was recrystallised from ethyl acetate/petroleum ether (60-80oC) to give the bicyclic compound (24) as fine white crystals m.p. 130-8°C,νmax (CHCl3) 1780 (strong) 1738, 1700, 1685, 1510, 1345cm-1. λmax (ethanol) 251 nm (∈ = 23,700) and 316 nm (∈= 16,700). δ ppm (CDCl3) 2.56 (2H, d, J 9 Hz, C4-H's) 2.74 (1H, dd, J 16Hz, 2.5 Hz, C6-H); 3.35 (1H, dd, J 16Hz, 5Hz, C6-H); 3.85 (1H, centre of m, C5-H); 5.24 (2H, s, CH2Ar); 5.26 (2H, s, CH2Ar); 6.76 (1H, s, NH); 7.15 - 7.55 (11H, Ar); 8.0-8.25 (2H, Ar).
EXAMPLE 10
Benzyl 3-p-nitrophenylthio-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
(a) Preparation of 1-(1'-Benzyloxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-(p-nitrophenylthiocarbon- ylmethyl)azetidin-2-one
[0157] The acid (12, prepared as in Example 4a) (4.39g) in dry tetrahydrofuran (150ml), under argon, was treated with triethylamine (1.78ml) and diethylphosphorochloridate (2.13g). After stirring at room temperature for 3 hours, the reaction mixture was added to freshly prepared sodium p-nitro- phenylthiolate in tetrahydrofuran at 0° [prepared by treating dried p-nitrophenylthiol (1.4g) in dry tetrahydrofuran (75ml), under argon at 0° with sodium hydride (0.426g of a 50% suspension in oil)].
[0158] The stirred red mixture was kept below 100 (internal temperature) for 1.5 hours. After reducing the volume by evaporation, ethyl acetate (500ml) was added, and the reaction mixture was washed with brine, dried over magnesium sulphate and filtered,and the filtrate was evaporated. Chromatography of the residue on silica 60 ( < 230 mesh) (80g), eluting with ethyl acetate gave the required thioester (25) (2.6g). Crystallisation from ethyl acetate/ether gave yellow crystals m.p. 169-70°C ν. max (CHCl3) 1745, 1720 (sh), 1630 cm-1. (Found:C, 67.53; H, 4.57; N, 3.93%. C38H31N206SP requires C, 67.66; H, 4.60; N, 4.15%.
(b) ' Preparation of Benzyl 3-P-nitrophenylthio-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
[0160] The phosphorane (25) (1.0g) in dry toluene (600ml) was heated under an atmosphere of argon under reflux using a Dean-Stark apparatus to remove water. After 1.5 hours the dark solution was rapidily cooled, evaporated almost to dryness, then chromatographed on 30g silica 60 (230-400 mesh). Elution with 30% ethyl acetate in petroleum ether (60°-80°C) gave the required product (26), (41mg) as yellow crystals from ethyl acetate m.p. 126-31°. ν max (CHC13) 1795, 1710, 1525, 1345cm-1.δ ppm [(CD3)2C0] 3.00 (2H, d, J 10Hz, C4-CH2), 3.07 (1H, dd, J 17, 4Hz, C6-H trans), 3.52 (1H, dd, J 17, 6Hz, C6-H cis), 4.21 (1H, m, C5-H), 5.36 (2H,`s, CH2), 7.47 (5H, m, Ph), 7.92 and 8.32 (4H, ABq, J 9Hz, SPhN02).λ max (EtOH) 261 nm (∈= 8,430), 312 nm ( ∈= 10,219) 343 nm (sh) ( ∈= 8,500).
EXAMPLE 11
Sodium 7-oxo-3-phenylthio-l-azabicyclo-[3.2.0]hept-2-ene― 2-carboxylate
[0162] The p-nitrobenzyl ester (18) (70mg) was dissolved in 30% aqueous dioxan containing 5% Pd/C (90mg) prenyarogenated for twenty minutes]. The solution was hydrogenated at ambient temperature and pressure for one hour. Examination of the solution by u.v. showed a shift of chromo- phoric absorption of 316 nm and 266 nm for the p-nitrobenzyl ester to 314 nm and 251 nm respectively for the product. The solution was treated with one equivalent of NaHC03 (14.7mg) in water (2ml) and filtered through keiselguhr. The organic solvent was removed under reduced pressure until cloudiness occurred and extracted with ethyl acetate (3 x 10ml). The water was evaporated to low volume (approx. 2ml) and loaded onto a biogel P2 column. Elution with water and collection of 10ml fractions gave the sodium salt in fractions 11 and 12. The solvent was evaporated under high vacuum, and the solid obtained by evaporation of solvent twice from ethanol (2 x 10ml) and twice from toluene (2 x 15ml) to yield (27) as a light yellow solid (12mg)· ν max (KBr disc) 1755cm-1 0 max (EtOH) 302 nm.
EXAMPLE 12
Phthalidyl 7-oxo-3-phenylthio-1-azabicyclo-[3.2.0]hept-2-ene-2-carboxylate
[0164] The sodium salt (14mg) was dissolved in DMF (2ml) and treated with bromophthalide (10mg). The solution was stirred at RT for 3 hours, the solvent was evaporated, and the residue was dissolved in ethyl acetate and washed with brine (2 x 5ml). The organic phase was dried (MgS04) and evaporated to yield an oil which after chromatography gave (28) as an oil (3mg) ν max (CHC13) 1795, 1730cm-1.δppm(CDC13) 2.69 (2H, d, J9.5 Hz, C4-CH2), 2.81 (1H, dd, J 16.5, 3.5Hz, C6-Ha), 3.38 (1H, dd, J16.5, 5.5Hz, C6-Hb) 4.07 (1H, m, C5-H) 6.55 (½H, s, C02CH from one isomer) 7.20 to 8.00 (9½H, m, aromatics plus C02CH from the second isomer) λmax 322 nm.
EXAMPLE 13
Pivaloyloxymethyl 7-oxo-3-phenylthio-1-azabicyclo [3.2.0] hept-2-ene-2-carboxylate
(a) Preparation of 1-(1-pivaloyloxycarbonyl-1'-triphenyl- phosphoranylidenemethyl)-4-carboxymethylazetidin-2- one
[0166] The phosphorane (d1.5, prepared as in Description 5) (258mg) was dissolved in dry methylene chloride (15ml) containing trifluoracetic acid (0.8ml) and stirred at RT. for ten minutes. The solution was cooled to -70° and ozonised for 15 minutes until a blue colour persisted. Argon was passed through the solution to remove excess ozone and m-chloroperbenzoic acid (90mg) in methylene chloride (5ml) was added. The mixture was allowed to warm up to RT. and stirred overnight. The solvent was evaporated and the residue chromatographed (Kieselgel 60,<230 mesh) to yield the phosphorane acid (29) as the trifluoroacetic acid salt. The salt was dissolved in methylene chloride and stirred with basic alumina (500mg) for one hour. The solution was filtered and evaporated to yield the phosphorane-acid (29) as a colourless foam (198 mg)ν max (CHC13) 1730, 1600cm-1.
(b) Preparation of 1-(1-pivaloyloxymethyloxvcarbonyl 1t-triphenylphosphoranylidenemethyl)-4-(phenylthio- carbonylmethyl)azetidin-2-one.
[0168] The acid (29) (187mg) was dissolved in dry THF containing Et3N (34mg) and a solution of diethylphosphorochloridate (61mg) in dry THF (2ml) was added dropwise under argon. The reaction was stirred at RT. for three hours and thallium (I) phenylthiolate (105mg) was added. The reaction was stirred overnight, filtered and the solvent evaporated. The resulting oil was chromatographed on Merck Kieselgel 60 (< 230 mesh) using ethyl acetate/petrol (60-80) as eluant to yield the title compound (30) as a colourless oil which crystallised from ether as a white solid m.p. 149-50° (120mg; 55%).ν max (CHCl3) 1735, 1700 (sh), 1630cm- 1
(c) Preparation. of pivaloyloxymethyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate
[0170] The phosphorane (30) (218mg) was refluxed in dry toluene (250ml) under argon for 18 hours. The solvent was evaporated and the residue chromatographed on florisil (200-300 U.S. mesh) using slight pressure and ethyl acetate/petrol (60-80) as eluant. The title compound (31) was collected as a colourless oil (6mg; 5%)ν max (CHCl3) 1780, 1750, 1725cm-1.δ ppm (CDCl3), 1.22 (9H, s, C(CH3)3) 2.62 (2H, d, J 9.5Hz, C4-CH2) 2.78 (1H, dd, J 16Hz, 3Hz, C6-H,trans), 3.36 (1H, dd, J 16Hz, 5Hz, C6-H, cis) 4.00 (1H, m, C5-H) 5.87 and 5.98 (2H, ABq, J 5.5Hz, OCH20) 7.40 (5H, m, Ph ) , λ max (EtOH) 319 nm.
PHARMACOLOGICAL DATA
In Vitro Antibacterial Testing Concentration of Compounds showing growth inhibition µg/m?
1. A compound of the formula (II):
characterised in that R1 is a group such that C02R1 is a carboxylic acid group or a salt or ester thereof and R2 is a phenyl group or a phenyl group substituted by one to four groups selected from lower alkyl, fluorine, chlorine, bromine, CN, N02, COR3, OR3, SR3, NH2, NHCOR3, NHC02R3, C02R3 or C02R,10 where R3 is lower alkyl, benzyl, fluorobenzyl, chlorobenzyl,.bromobenzyl or nitrobenzyl and C02R10 is carboxyl or a salt thereof, not more than three such groups being selected from fluorine, chlorine, bromine, CN, N02, NH2, COR3 or C02R3 and not more than two such groups being selected from CN, N02 or NH2.
characterised in that R1 is a group such that C02R1 is a carboxylic acid group or a salt or ester thereof and R2 is a phenyl group or a phenyl group substituted by one to four groups selected from lower alkyl, fluorine, chlorine, bromine, CN, N02, COR3, OR3, SR3, NH2, NHCOR3, NHC02R3, C02R3 or C02R,10 where R3 is lower alkyl, benzyl, fluorobenzyl, chlorobenzyl,.bromobenzyl or nitrobenzyl and C02R10 is carboxyl or a salt thereof, not more than three such groups being selected from fluorine, chlorine, bromine, CN, N02, NH2, COR3 or C02R3 and not more than two such groups being selected from CN, N02 or NH2.
2. A compound according to claim 1, characterised in that R2 is a phenyl group or a phenyl group substituted by one or two groups selected from
fluorine, chlorine, bromine, CN, N02, COR3, OR3' NHCOR3, NHC02R3 or C02R3 where R3 is a lower alkyl or benzyl group.
3. A compound according to claim 2, characterised in that R1 is a group such that C02R1 is an ester group.
4. A compound according to any one of claims 1, 2 or 3 characterised in that R2 is phenyl, p-nitrophenyl, p-aminophenyl, p-acetamidophenyl or p-(4'-nitrobenzyloxy-
carbonylamino)phenyl.
.5. A compound according to any one of claims 1, 2, 3 or 4 characterised in that R1 is phthalidyl.
6. A compound according to any one of claims 1, 2, 3 or 4 characterised in that R1
is p-nitrobenzyl.
7. A compound according to any one of claims 1, 2 or 4 characterised in that R1 is a group such that the compound is a carboxylic acid salt.
8. A compound according to claim 7 characterised in that R1 is sodium or potassium.
9. A compound according to claim 1, which compound is selected from t-butyl 7-oxo-3-p-nitrophenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate,
t-butyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2- ene-2-carboxylate,
methyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2- ene-2-carboxylate,
benzyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2- ene-2-carboxylate,
p-nitrobenzyl 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate,
benzyl 7-oxo-3 p-acetamidophenylthio-1--azabicyclo[3.2.0] hept-2-ene-2-carboxylate,
benzyl 7-oxo-3-aminophenylthio-1-azabicyclo[3.2.0] hept-2-ene-2-carboxylate.
benzyl '7-oxo-3-:e.-(4'-nitrobenzyloxycarbonylamino)phenyl- thio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate, ;
benzyl 7-oxo-3-p-nitrophenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate, .
sodium 7-oxo-3-phenylthio-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate,
phthalidyl 7-oxo-3-phenylthio-1-azacibycylo[3.2.0]hept-2-ene-2-carboxylate or
pivaloyloxymethyl 7-oxo-3-phenyl-1-azabicyclo [3.2.0] hept-2-ene-2-carboxylate.10. A pharmaceutical composition characterised in that it comprises a compound according
to any one of claims 1-9 and a pharmaceutically acceptable carrier.
11. A process for the preparation of a compound according to claim 1, characterised
in that it comprises
a) the ring closing elimination of the elements of O = PR4R5R6 from a compound of the formula (VII):
wherein C02R1 is an ester group, as defined in claim 1 and R4, R5 and R6 are each lower alkyl, phenyl or diloweralkylamino groups,
b) thereafter isolating the ester of the formula (II) according to claim 1 so formed,
c) where desired de-esterifying the ester to form a free acid or its salt,
d) and thereafter optionally salifying or esterifying the free carboxylic acid so formed, or
e) thereafter optionally converting the salt so formed into a free carboxylic acid, an ester or another salt.
12. A process for the preparation of a compound according to claim 3 characterised
in that it comprises the ring closing elimination of the elements of 0 = PR4R5R6 from a compound of the formula (VII):
wherein C02R1 is an ester group, as defined in claim 3, and R4, R5 and R6 are each lower alkyl, phenyl or diloweralkylamino groups.
wherein C02R1 is an ester group, as defined in claim 3, and R4, R5 and R6 are each lower alkyl, phenyl or diloweralkylamino groups.
13. A method of treatment and/or prophylaxis of bacterial infections in human beings
or domestic animals, characterised by the administration to the sufferer of an effective
amount of a compound according to any one of claims 1-9.
14. A method or treatment and/or prophylaxis of bacterial infections in human beings
or animals, characterised by the administration to the sufferer of an effective amount
of a compound according to claim 3.