Abstract: Disclosed are compounds of the general formula: ##STR1## wherein R.sub.1 is amino, an acylated amino or a protected amino group, X is hydrogen or methoxy, and R' is hydrogen, R or R.sup.4 wherein R is an organic residue attached to the azetidine ring through a carbon atom therein and R.sub.4 is azido, a halogen, an amino group which may optionally be acylated or a group of the formula ##STR2## wherein R.sub.5 is an organic residue and n is 0, 1 or 2, and pharmaceutically acceptable salts and esters thereof.The compounds have antimicrobial and/or .beta.-lactamase-inhibitory activity and are of value as drugs for human beings and domesticated animals.

Abstract: 4-Cyano-2-azetidinone derivatives represented by the formula ##STR1## wherein R.sup.1 is an amino group which may be acylated or protected, X is a hydrogen atom or a methoxy group and W is a hydrogen atom or a sulfo group, and methods of producing the same, for example, as represented by ##STR2## wherein R.sup.2 is an acylated or protected amino group, Y is a halogen atom or a group having the formula --OCOR.sup.3, --SCOR.sup.3 or --S(O).sub.n --R.sup.3 (R.sup.3 being a hydrocarbyl group and n an integer 1 or 2), R.sup.4 is an amino group which may be acylated or protected and X is as defined above. Compounds [I] are useful as advantageous intermediates for the synthesis of optically active 4-substituted-2-azetidinone derivatives, and, when W=SO.sub.3 H, [I] are also useful as antimicrobial agents and as beta-lactamase inhibitors.

Abstract: Disclosed are compounds of the general formula: ##STR1## wherein R.sub.1 is amino, an acylated amino or a protected amino group, X is hydrogen or methoxy, and R' is hydrogen, R or R.sup.4 wherein R is an organic residue attached to the azetidine ring through a carbon atom therein and R.sub.4 is azido, a halogen, an amino group which may optionally be acylated or a group of the formula --OR.sub.5, ##STR2## or --S--S--R.sub.5 wherein R.sub.5 is an organic residue and n is 0, 1 or 2, and pharmaceutically acceptable salts and esters thereof.The compounds have antimicrobial and/or .beta.-lactamase-inhibitory activity and are of value as drugs for human beings and domesticated animals.

Abstract: Compounds of the formula ##STR1## are useful as intermediates in preparing 1-sulfo-2-oxoazetidine compounds having the carbamoyloxymethyl group at the 4-position. The final product compounds have antimicrobial and/or .beta.-lactamase-inhibitory activity and are of value as drugs for human beings and domesticated animals.

Abstract: Disclosed are compounds of the general formula: ##STR1## wherein R.sup.1 is a hydrogen atom or a lower alkyl group and R.sup.2 is a hydrogen atom or an ester residue, said derivative having the (3S,4S)-configuration; and pharmaceutically acceptable salts and esters thereof.The compounds have antimicrobial and/or .beta.-lactamase-inhibitory activity and are of value as drugs for human beings and domesticated animals.

Abstract: 4-Cyano-2-azetidinone derivatives represented by the formula ##STR1## wherein R.sup.1 is an amino group which may be acylated or protected, X is a hydrogen atom or a methoxy group and W is a hydrogen atom or a sulfo group, and methods of producing the same, for example, as represented by ##STR2## wherein R.sup.2 is an acylated or protected amino group, Y is a halogen atom or a group having the formula --OCOR.sup.3, --SCOR.sup.3 or --S(O).sub.n --R.sup.3 (R.sup.3 being a hydrocarbyl group and n an integer 1 or 2), R.sup.4 is an amino group which may be acylated or protected and X is as defined above. Compounds [I] are useful as advantageous intermediates for the synthesis of optically active 4-substituted-2-azetidinone derivatives, and, when W=SO.sub.3 H, [I] are also useful as antimicrobial agents and as beta-lactamase inhibitors.