Thiazolyl Penicillins and their Preparation

1,179,856. Penicillins. ASTRA A.B. 20 March, 1968 [20 March, 1967], No. 12880/67. Heading C2A. The invention comprises a thiazolylmethyl or substituted thiazolylmethyl penicillin of Formula I wherein R1 is H, C 1 -C 6 alkyl, alkenyl or alkynyl, or a monocarbocyclic aryl group of 6 to 10 C atoms; and R2 is thiazolyl which is unsubstituted or substituted with a halogen atom or with a C 1 -C 6 alkyl, OH, C 1 -C 6 alkoxy, C 1 -C 6 alkanoyloxy or monocyclic heterocyclic group, with aralkyl of up to 10 C, with a monocarbocyclic aryl, aryloxy or aroyloxy of 6 to 10 C atoms, or with an amino group or amino substituted with C 1 -C 6 alkyl, C 6 -C 10 aryl or aralkyloxycarbonyl of up to 10 C atoms; the group R2, when a thiazol-4-yl group, being substituted other than with a C 1 -C 6 alkyl; or a non-toxic salt thereof. Typical compounds are 6 - [α - (2 - chlorothiazol - 4 - yl) acetamido] penicillanic acid and 6-[α-(2-phenyl thiazol-4-yl) acetamido] penicillanic acid. Salts are formed with metals (e.g. potassium, calcium and aluminium) and amines (e.g. procaine and dihydroabietylamine). The penicillins are prepared by reacting a compound of formula R1R2-COX, wherein R1 and R2 have the above meanings, with 6-aminopenicillanic acid, or a salt thereof, in an organic or aqueous organic solution, or with a derivative of 6-APA of formula in an organic solution, wherein R3 is a trialkylsilyl group, is a phenacyl group, which is unsubstituted or substituted with a halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy or NO 2 , or is a group of formula wherein R4, R5 and R6 are monovalent hydrocarbon groups; CO-X and Y-NH being groups of atoms capable of reacting with each other with formation of the -CONH- group or C-N bond which is then hydrolysed to the -CONH- group. Pharmaceutical compositions comprise thiazolylmethyl penicillins of Formula I and a carrier. They are antibacterials, nutritional supplements in animal feeds and may be used for the treatment of mastitis in cattle.