| 摘要 |
<p>1442435 Pentachlorophenyl esters of penicillins and cephalosporins BIOCHEMIE GmbH 31 Aug 1973 [5 Sept 1972] 41090/73 Heading C2C The novel pentachlorophenyl esters of cephalosporanic acids and penicillanic acids are prepared by reacting the penicillin or cephalosporin or a reactive derivative thereof (e.g. a mixed anhydride) with pentachlorophenol or a reactive derivative thereof (e.g. pentachlorophenylsulphite), if required in the presence of a condsneation agent such as dicyclohexylcarbodiimide or carbonyldiimidazole, or an acid binding agent. The preferred novel esters have the general Formula (III) in which B is a radical (IVa) or (IVb) wherein n is 0 or 1, and R is hydrogen, formyl, trityl, tritylsulphenyl, benzyloxycarbonyl, pnitrobenzyloxycarbonyl, 2,2,2-trichloroethoxycarbonyl, o-nitrophenylsulphenyl, tert-butyloxycarbonyl, a group of Formula (V) in which m is 0 or 1 and R 1 is phenyl, cyclohexyl, cyclohexadienyl, thien - 2 - yl, thien - 3 - yl, 2,6 - dimethoxyphenyl, 3 - o - chlorophenyl - 5- methyl - isoxazol - 4 - yl, 3 - (2,6 - dichlorophenyl) - 5 - methyl - isoxazol - 4 - yl, or phenyl or cyclohexyl substituted by one or more of C 1-6 alkyl, C 1-6 alkoxy, halogen, hydroxy and amino, or m is 1 and R 1 is cyano; or R may further be a group of Formula (VI) in which X is oxygen or sulphur, R 2 is hydrogen, C 1-6 alkyl, or phenyl, and R 1 is as defined above; or a group of Formula (VII) in which R 3 is straight or branched chain C 1-12 alkyl which may be interrupted by O or S; or a group of Formula (VIII) in which R 4 is sulphonyl, azido, carboxyl, hydroxy, amino or amino protected by trityl, tritylsulphenyl, benzyloxycarbonyl, p-nitrobenzyloxycarbonyl, 2,2,2 - trichloroethoxycarbonyl, o-nitrophenylsulphenyl, or tertbutyloxycarbonyl. The pentachlorophenyl group provides a protecting group whereby various modifications (e.g. 6- or 7-acylation, or oxidation of penicillins to the S-oxide followed by ring expansion to give corresponding cephalosporins) may be effected in another part of the molecule, followed by removal of the pentachlorophenyl group, Such removal may be effected by treatment with dilute NaOH or an organic base such as triethylamine or preferably imidazole in the presence of water, in which case the penicillin or cephalosporin product may be isolated as the corresponding base salt. Starting materials prepared are Di-pentachlorophenyl sulphite, by reaction of pentachlorophenol and thionyl chloride; and D-α-tritylsulphenylaminophenyl-acetic acid, by reacting tritylsulphenyl chloride with D-α-aminophenyl acetic acid methyl ester hydrochloride to give D -α- tritylsulphenylaminophenyl - acetic acid methyl ester and hydrolysing the methyl ester group.</p> |
