Abstract: Cephalosporin antibiotics of formula ##STR1## (where R is thienyl or furyl; R.sup.a and R.sup.b are each selected from hydrogen, C.sub.1-4 alkyl, C.sub.2-4 alkenyl, C.sub.3-7 cycloalkyl, phenyl, naphthyl, thienyl, furyl, carboxy, C.sub.2-5 alkoxycarbonyl and cyano, or R.sup.a and R.sup.b together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene or cycloalkenylidene group; m and n are each 0 or 1 such that the sum of m and n is 0 or 1; and P is hydrogen or halogen) and their non-toxic derivatives exhibit broad spectrum antibiotic activity characterized by particularly high activity against gram negative microorganisms, including those which produce .beta.-lactamases. The compounds, which are syn isomers or exist as mixtures of syn and anti isomers containing at least 90% of the syn isomer, have particularly high in vitro activity against strains of Escherichia coli, Haemophilus influenzae and Proteus organisms; compounds wherein at least one of R.sup.a and R.sup.

Abstract: The invention relates to novel semisynthetic intermediates or relay compounds of use in the production of cephalosporins and related .beta.-lactam antibiotic compounds. The novel compounds are 3-hydroxy- and 3-oxo-7-amino- and blocked amino --(6R,7R)-cephams. Process for the preparation of the novel compounds are described and exemplified.