GB1441587A - Cephalosporin compounds - Google Patents

Abstract

1441587 7 - Acylamino - 3 - methylceph- 3-em-4-carboxylic acids GLAXO LABORATORIES Ltd 29 June 1973 [14 July 1972] 33151/72 Addition to 1312233 Heading C2C 7# - Acylamido - 3 - methylceph - 3 - em- 4-carboxylic acids are prepared by the molecular rearrangement of a 6#-acylamidopenicillanic acid 1-oxide by heating the penicillin oxide in the presence of a catalyst comprising a mono-O-substituted orthophosphoric acid or a salt thereof with an aromatic heterocyclic tertiary nitrogen base having a pKb of not less than 4 (which salt may be formed in situ in the reaction mixture). Mono-O-substituted orthophosphoric acids may be aliphatic, araliphatic or aryl dihydrogen phosphates, of which the hydrocarbyl groups may be substituted, e.g. phenyl-, p-nitrophenyl, 2-chloromethyl-4-nitrophenyl, and 2,2,2-trichloroethyl hydrogen phosphate. The base may be pyridine, quinoline, picoline, isoquinoline, benzimidazole, and 2- and 4-methyl-quinoline, and such bases substituted by, e.g. halogen, acyl, acylamido, cyano, carboxy or aldoximino groups. When the base is used as a phosphoric acid salt, either the base or the acid may be present in excess of the equivalent amount. A preferred salt is pyridinium 2,2,2-trichloroethyl dihydrogen phosphate.