Abstract: The compounds of the formula (II): ##STR1## and salts and esters thereof wherein R.sub.1 is an inert organic group of up to 14 carbon atoms and R.sub.2 is an inert organic group of up to 16 carbon atoms, the group NR.sub.1 R.sub.2 containing up to 22 carbon atoms, are antibacterial agents able to enhance the effectiveness of penicillins and cephalosporins against certain .beta.-lactamase producing bacteria.

Abstract: Compounds of the formula (I): ##STR1## and salts and esters thereof, wherein R.sub.1 is a hydrogen atom or a lower alkyl, aryl or aralkyl group, R.sub.2 and R.sub.3 are independently hydrogen, aryl, aralkyl, lower alkyl or substituted lower alkyl, or R.sub.3 is joined to R.sub.1 to form a 4-, 5-, or 6- membered ring or is joined to R.sub.2 to form a 5- or 6- membered ring with the proviso that when R.sub.2 is hydrogen, R.sub.1 is not hydrogen and R.sub.1 and R.sub.3 are not joined to form a group of the sub-formula (a) ##STR2## wherein R.sub.4 is a hydrogen atom or a NH.CO.R.sub.5 group wherein R.sub.5 is a lower alkyl, lower alkoxy lower alkyl, aryl, aralkyl, aryloxyalkyl, lower alkoxy or aryloxy group have .beta.-lactamase inhibitory and anti-bacterial properties.

Abstract: The compounds of the formula: ##STR1## and salts and esters thereof are useful agents for the treatment of bacterial infections either alone or in combination with a penicillin or cephalosporin derivative.The preceding compounds may be prepared by the hydrogenation of a compound of the formula: ##STR2## wherein R is a hydrogen atom or an acyl group or a salt or ester thereof.

Abstract: The compounds of the formula (II): ##STR1## and salts and esters thereof wherein R is an inert organic group of up to 18 carbon atoms and are able to inhibit the action of various bacterial .beta.-lactamases. Thus when a compound of the formula (II) or its salt or ester is used together with a penicillin or cephalosporin, the effectiveness of that penicillin or cephalosporin can be considerably enhanced. These novel synergysts can be prepared by etherification of an ester of clavulanic acid followed if desired by de-esterification. The novel synergysts also possess antibacterial activity.

Abstract: This invention provides the compounds of the formula (II): ##STR1## and salts and esters thereof, wherein R.sub.1 is H and R.sub.3 is H or an aryl, aralkyl, lower alkyl or substituted lower alkyl group or R.sub.1 and R.sub.3 are joined so that the CHR.sub.1.NH.CO.R.sub.3 moiety forms a group of the sub-formula (a): ##STR2## wherein R.sub.4 is a hydrogen atom or a NH.CO.R.sub.5 group wherein R.sub.5 is a lower alkyl, lower alkoxy lower alkyl, aryl, aralkyl, aryloxyalkyl, lower alkoxy or aryloxy group.The compounds have .beta.-lactamase inhibitory and anti-bacterial properties.The invention also provides a process for their preparation, and pharmaceutical compositions containing them.

Abstract: Compounds of the formula ##STR1## and salts thereof are useful both for their antibacterial activity and as synergists in combination with penicillins and cephalosporins.

Abstract: .beta.-Lactamase inhibitory and antibacterial compounds of the formula: ##STR1## wherein R is a hydrogen atom or an acyl group and salts and esters thereof, are produced and pharmaceutical compositions containing the same.

Abstract: Compounds of the formula ##STR1## and salts and esters thereof wherein R.sub.1 is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl, alkenyl of 2 to 4 carbon atoms, alkynyl of 2 to 4 carbon atoms, acyl of 1 to 4 carbon atoms, a carboxylic acid group or ester thereof of 1 to 7 carbon atoms, or alkyl of 1 to 4 carbon atoms substituted by 1 or 2 halogen atoms, hydroxyl, substituted hydroxyl, amino, protected amino, substituted thio of 1 to 7 carbon atoms, substituted sulphinyl of 1 to 7 carbon atoms, substituted sulphonyl of 1 to 7 carbon atoms, or by a carboxylic acid group or ester thereof of 1 to 7 carbon atoms;R.sub.2 is hydrogen or alkyl of 1 to 4 carbon atoms, or is joined to R.sub.1 to form a cycloalkyl group of 3 to 6 carbon atoms;R.sub.3 is hydrogen, chlorine or bromine; andR.sub.4 is hydrogen, halogen, azido or amino; provided that when R.sub.4 is azido, R.sub.3 is hydrogen and R.sub.1 is methyl,R.sub.2 is not methyl, and that when R.sub.2 R.sub.3 and R.sub.4 are hydrogen andR.sub.

Abstract: Compounds of the formula ##STR1## wherein CO.sub.2 R is an ester group, are useful for their .beta.-lactamase inhibitory activity.

Abstract: .beta.-Lactamase inhibitory and antibacterial compounds of the formula: ##STR1## wherein R is a hydrogen atom or an acyl group and salts and esters thereof, procedure for their preparation and pharmaceutical compositions containing the same.

Abstract: A new antibacterially active agent has been isolated from Streptomyces clavuligerus. This new compound which is designated clavulanic acid has the formula (I): ##STR1## In addition to being a broad spectrum antibiotic of medium potency, clavulanic acid and its salts and esters have the ability to enhance the effectiveness of .beta.-lactam antibiotics against many .beta.-lactamase producing bacteria.

Abstract: The compound of the formula (II): ##STR1## and its pharmaceutically acceptable salts and esters may be produced by ozonolysis of clavulanic acid and its derivatives. The compound has antibacterial and .beta.-lactamase inhibiting activity.