Abstract: Novel antibiotic compounds which are 7.beta.-acrylamidoceph-3-em-4-carboxylic acids, and 6.beta.-acrylamidopenam-3-carboxylic acids and non-toxic derivatives thereof wherein the acrylamido group has the structure ##STR1## wherein A is aryl group and B is a substituted or unsubstituted lower alkyl, lower alkenyl or lower alkynyl group; or an aryl, cycloalkyl or cycloalkenyl group. These compounds possess antibacterial activity against gram-positive and gram-negative organisms coupled with stability to .beta.-lactamases. The invention further relates to the administration of the compounds.

Abstract: 2-Aryl-2-hydroxyiminoacetic acids rich in the syn isomer are prepared by reaction of an arylglyoxylic acid with hydroxylamine in an aqueous reaction medium, e.g. water, in the presence of a source of magnesium, calcium or zinc ions, e.g. magnesium hydroxide. The acids so obtained are of value as synthetic intermediates in the preparation of penicillin and cephalosporin antibiotics containing syn-2-aryl-2-hydroxyiminoacetamido side chains.