American Cyanamid Company

Robert E Babine

Ving J Lee

Allan Wissner

William V Curran

Michael Peter Trova

Nan Zhang

Steven R Schow

Compounds of the formula I: ##STR1## wherein X, Y, Z, a, b, c, R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are defined in the specification are provided. The compounds are useful as inhibitors of retroviral protease enzymes.

Retroviral protease inhibitors

Diphenylmethyl esters of cephalosporins, and processes for synthesizing such, are described and disclosed.

3-substituted-8-oxo-7-substituted-thioxomethylamino-5

Cephalosporins active as antibacterial agents, and processes for synthesis of such agents, are disclosed.

3-[2-thiazoloamino]-8-oxo-7-substituted-5-thia-1-a

Compounds of the formula: ##STR1## wherein R.sub.1 is hydrogen, alkyl(C.sub.1 -C.sub.3), vinyl, acetyloxy or ##STR2## wherein R.sub.3 is hydrogen or alkyl(C.sub.1 -C.sub.6); R.sub.2 is hydrogen or diphenylmethyl and A is R.sub.4 --C, where R.sub.4 is acetyl or benzoyl, are useful as intermediates in the preparation of biologically active cephalosporin derivatives.

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Nanuet, NY, United States of America

Robert E Babine