Abstract: The invention is concerned with .DELTA..sup.3 -4-carboxy cephalosporin antibiotics possessing a 3-vinyl or substituted 3-vinyl groups as well as with phosphorous intermediates useful in the preparation thereof.

Abstract: A process for the production of an ester of one enantiomer of an .alpha.-amino acid in the form of a salt with an optically active acid, which comprises reacting an ester of the opposite enantiomer of said .alpha.-amino acid (which may be in admixture with an ester of the desired enantiomer) with said optically active acid and an aldehyde or ketone, whereby an ester of the desired enantiomer separates out in the form of the said salt. The free .alpha.-amino acid and/or its salts may be obtained by hydrolysis of the ester thus formed.Optically active .alpha.-amino acids and their esters are of use in the synthesis of physiologically active compounds e.g. antibiotics of the penicillin and cephalosporin types. The present invention provides a relatively cheap, high yield process for the production of esters of optically active .alpha.-amino acids and for the production of optically active .alpha.-amino acids thereform. Certain novel compounds are disclosed.