Abstract: Compounds of general formula (I) ##STR1## (where R.sup.1 is a carboxyl group, a group COO.sup..crclbar. or a blocked carboxyl group;R.sup.2 is an amino or protected amino group; andR is hydrogen or a group of the formula CH.sub.2 X, where X represents a halogen atom, a hydroxyl group, an acetoxy group; a group of the formula O.CO.NHR.sup.3, where R.sup.3 is hydrogen, a C.sub.1-4 alkyl group optionally substituted by 1 to 3 halogen atoms or an N-protecting group; a group of the formula OR.sup.4, where R.sup.4 is a C.sub.1-4 alkyl group optionally substituted by halogen or a C.sub.1-4 alkoxy group; or a pyridinium, 3-carbamoyl-pyridinium or 4-carbamoyl-pyridinium group;B is --S-- or --SO-- (.alpha.- or .beta.-); and the dotted line bridging the 2-, 3- and 4- positions indicates that the compound is a ceph-2-em or ceph-3-em compound) and salts thereof, the compounds of formula (I) being associated with an anion when X represents a pyridinium, 3-carbamoylpyridinium group or a 4-carbamoylpyridinium group and R.

Abstract: The present invention provides compounds of general formula (III) ##STR1## [wherein R is an amino or protected amino group;R.sup.2a is a straight or branched chain alkyl group containing from 1 to 4 carbon atoms, an allyl, but-2-enyl or but-3-enyl group, or is a group of formula ##STR2## (wherein each of R.sup.3 and R.sup.4 is independently a hydrogen atom or a methyl or ethyl group, or R.sup.3 and R.sup.4 taken together with the carbon atom to which they are attached may be a cycloalkylidene group containing from 3 to 5 carbon atoms, and R.sup.5 is a hydrogen atom or a carboxyl blocking group);Y represents a 1-methyl-1-pyrrolidinium group andR.sup.7 represents the group --COO.sup.- or --COOR.sup.6, where R.sup.6 is a hydrogen atom or a carboxyl blocking group] and salts thereof.

Abstract: The invention provides crystalline (Z)-2-(2-t-butoxycarbonyl-prop-2-oxyimino)-2-(2-triphenylmethylaminothiazo l-4-yl)acetic acid in association with dioxan and its crystalline ethyl ester in association with methanol. The compounds are of value as intermediates in the preparation of .beta.-lactam antibiotics such as ceftazidime or azthreonam.

Abstract: Cephalosporin antibiotics of general formula ##STR1## (wherein R.sup.1 represents a hydrogen atom or a methyl or 2-chloroethyl group) and non-toxic salts and non-toxic metabolically labile esters thereof. The compounds exhibit broad spectrum antibiotic activity and have high activity against both Gram-positive and Gram-negative organisms, including many .beta.-lactamase producing strains. Processes for the preparation of the compounds and pharmaceutical compositions containing them are described.

Abstract: The invention provides crystalline (Z)-2-(2-t-butoxycarbonyl-prop-2-oxyimino-2-(2-triphenylmethylaminothiazol -4-yl)acetic acid in association with dioxan and its crystalline ethyl ester in association with methanol. The compounds are of value as intermediates in the preparation of .beta.-lactam antibiotics such as ceftazidime or azthreonam.

Abstract: Novel semisynthetic .beta.-lactam intermediates of use in the production of cephalosporins, penicillins and related .beta.-lactam antibiotic compounds are provided. The novel compounds are prepared from .beta.-lactams obtained by cleavage of the 1,2-sulphur-carbon bond of a penicillin 1-oxide (with subsequent internal or external trapping of the sulphur atom to leave a residual substituent as the .beta.-lactam nitrogen) by removal of the said residual substituent by an oxidative cleavage reaction.

Abstract: Novel semisynthetic 4-thio-azetidin-2-one derivatives of use in the production of cephalosporins, penicillins and related .beta.-lactam antibiotic compounds are provided by cleavage reactions involving the corresponding 4-dithio-azetidin-2-one derivative or a suitable thiazoline derivative, which starting materials may be obtained from penicillins without changing the configuration of the .beta.-lactam structure desired in the final product.