Abstract: This invention relates to pyrimidine derivatives for treating material and bacterical infestions in humans and animals.

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 synthetic .beta.-lactam antibacterial compounds, a process for their preparation and pharmaceutical compositions containing them.The compounds are those of the formula (II): ##STR1## wherein: R.sub.1 is a group such that CO.sub.2 R.sub.1 is a carboxylic acid group or a salt or ester thereof; and R.sub.2 is a phenyl group or a phenyl group substituted by one to four groups selected from lower alkyl, fluorine, chlorine, bromine, CN, NO.sub.2, COR.sub.3, OR.sub.3, SR.sub.3, NH.sub.2, NHCOR.sub.3, NHCO.sub.2 R.sub.3, CO.sub.2 R.sub.3 or CO.sub.2 R.sub.10 where R.sub.3 is lower alkyl, benzyl, fluorobenzyl, chlorobenzyl, bromobenzyl or nitrobenzyl and CO.sub.2 R.sub.10 is carboxyl or a salt thereof, not more than three such groups being selected from fluorine, chlorine, bromine, CN, NO.sub.2, NH.sub.2, COR.sub.3 or CO.sub.2 R.sub.3 and not more than two such groups being selected from CN, NO.sub.2 and NH.sub.2.

Abstract: Compounds of the formula ##STR1## and pharmaceutically acceptable salts thereof and antimalarial and antibacterial compositions containing an effective amount of active agent and a pharmaceutically acceptable carrier particularly in oral dosage form wherein R is hydrogen, methyl or ethyl; X is alkylene of 1-10 carbon atoms; Y is oxygen, sulphur or a bond, and Ar is an optionally substituted aryl moiety; are useful for their antimalarial and antibacterial activity.

Abstract: Antibacterial agents have been prepared of the formula (II): ##STR1## wherein R.sub.1 is a group such that CO.sub.2 R.sub.1 is an ester group and R.sub.2 is a hydrocarbon of up to 7 carbon atoms optionally substituted by CN, NO.sub.2, OR.sub.3, NH.CO.R.sub.3 or CO.sub.2 R.sub.3 wherein R.sub.3 is a lower alkyl.

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.