SUBSTITUTED PENICILLANIC ACIDS

1476981 6 - (D) - (-) - - amino - - (pacetoxyphenylacetamido)penicillanic acid BRISTOL MYERS CO 19 March 1975 [5 June 1974 19 Nov 1974] 24848/74 and 50016/74 Heading C2C The invention comprises the title compound [substantially free from L-(+ )-isomer], and its pharmaceutically acceptable salts. In examples, this compound is prepared by reacting aminopenicillanic acid or its trimethylsilyl ester with the acid chloride hydrochloride, of D-(-)-p-acetoxyphenylglycine, and (where applicable) hydrolysing the intermediate trimethylsilyl ester of the product. The title compound may be treated in aqueous solution with an esterase to give the p-hydroxyphenyl analogue. Therapeutic compositions having antibacterial activity, and which may be administered orally or parenterally, comprise either the title compound, or the p-hydroxyphenyl analogue which has been prepared from it.