Abstract p-Nitrobenzyl (2R, 3R)-2-(benzothiazol-2′-yldithio)-α-isopropylidene-4-oxo-3- phenoxyacetyl-aminoazetidine-1-acetate (7), readily prepared from penicillin V, can be converted into the corresponding 2-allylthio compound (2) by addition of allyl bromide and
