2-beta-alkenylpenamsulfone as beta-lactamase inhibitor

PURPOSE: To provide new compounds inhibiting a pathogen forming-lactamase by providing extremely excellent β-lactamase inhibiting properties and combining them with β-lactam antibiotic such as cephalosporins. CONSTITUTION: A compound of formula I (wherein one of R 1 and R 2 is -CN, a halogen or the like and the other is H, a lower alkyl or the like or both R 1 and R 2 form together a γ-lactam ring; R 3 is H, allyl or the like; n is 0-2) and salts thereof, e.g. benzhydryl (E/Z)-(2S,3S,5R)-3-(2-cyanoethenyl)-3-methyl-7- oxo-4-thia-1-aza-bicyclo[3,2,0]heptane-2-carboxylate. The compounds are obtd. by reacting a compd. of formula II with a compd. of formula III [wherein R 8 is PO(O-alkyl), a halogen or the like] in the presence of an active agent such as triethylamine. In addition, the compd. of formula II is obtd. by reacting e.g. an alcohol of formula IV with oxalyl chloride in dichloromethane in the presence of triethylamine. COPYRIGHT: (C)1995,JPO