4-thia-1-aza-bicyclo›4,2,0!oct-2-ene antibiotics

A compound selected from the group consisting of a compound of the formula ##STR1888## wherein R is selected from the group consisting of ##STR1889## ##STR1890## R.sub.a is selected from the group consisting of ArO--CH.sub.2 --, ArS--CH.sub.2 -- and ##STR1891## Ar and R.sub.b are individually selected from the group consisting of phenyl and phenyl substituted with at least one member of the group consisting of halogen, alkyl and alkoxy and alkylthio of 1 to 4 carbon atoms, alkylsulfinyl and alkylsulfonyl of 1 to 4 carbon atoms, --NH.sub.2, nitro, --OH, aminoalkyl of 1 to 4 carbon atoms, --CN and --CF.sub.3, R.sub.f is alkyl of 1 to 4 carbon atoms, R.sub.d is selected from the group consisting of a) hydrogen, b) alkyl of 1 to 6 carbon atoms, c) alkenyl and alkynyl of 2 to 6 carbon atoms, and d) cycloalkyl of 3 to 8 carbon atoms unsubstituted or substituted with a member of the group consisting of halogen, acyl of 1 to 7 carbon atoms, --CN, carbamoyl, amino, --OH, --SH, alkylthio and alkoxy of 1 to 4 carbon atoms, oxo, carboxyl and salified or esterified carboxyl, R.sub.1A is selected from the group consisting of ##STR1892## R'.sub.A and R'.sub.B are individually selected from the group consisting of hydrogen and alkyl of 1 to 4 carbon atoms, Z.sub.A is selected from the group consisting of a simple bond, --O--, --S-- and oxidized sulfur, R.sub.3A is selected from the group consisting of phenyl, diphenyl, naphthyl, thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, triazolyl, thiadiazolyl, oxadazolyl, tetrazolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, thiazinyl, oxazinyl, triazinyl, thiadiazinyl, oxadiazinyl, tetrazinyl, imidazolinyl, benzimidazolyl, benzothiazolyl and benzoxazole being unsubstituted or substituted with at least one member of the group consisting of a) alkyl of 1 to 4 carbon atoms unsubstituted or substituted with at least one member of the group consisting of carbocyclic aryl and carbocyclic aryloxy where the carbocyclic aryl is phenyl, diphenyl or naphthyl, alkyl, alkoxy, carbonyl, halogen, --OH, protected --OH, carboxy, salified or esterified carboxy, --NH.sub.2, acetamido, monoalkylamino and dialkylamino, b) alkenyl and alkynyl of 2 to 4 carbon atoms, c) carbocyclic aryl, d) halogen, e) --NH.sub.2, f) --NO.sub.2, g) alkoxy and alkylthio of 1 to 4 carbon atoms, h) --OH or --SH, i) free, salified or esterified carboxy, j) carbamoyl and k) cyclopentyl or cyclohexyl, R.sub.4 is selected from the group consisting of hydrogen and methoxy, A is selected from the group consisting of hydrogen, alkali, metal, alkaline earth metal, magnesium, --NH.sub.2, an organic amine selected from the group consisting of methylamine, propylamine, trimethylamine, diethylamine, triethylamine, N,N-dimethylthanolamine, tris(hydroxymethyl)amino methane, ethanolamine, pyridine, picoline, dicyclohexylamine, morpholine, benzylamine, procaine, lysine, arginine, histidine, and N-methylglucamine and esterified carboxy, n.sub.2 is an integer from 0 to 2 or a non-toxic, pharmaceutically acceptable acid addition salt.