THE earlier confusion regarding the structure of vitamin A2was removed by its synthesis1, which conclusively proved it to have the dehydrovitamin A1formula suggested by Morton, Salah and Stubbs2. In this synthesis an extra double bond was introduced into the β-ionone ring of the methylester of vitamin A1acid, by bromination with N-bromosuccinimide, followed by dehydrobromination with 4-phenyl morpholine. Reduction with lithium aluminium hydride gave a product which closely agreed with the spectroscopic properties of vitamin A2. Recently, Henbest, Jones and Owen3carried out an elegant conversion of vitamin A1to A2by treating the aldehyde of vitamin A1(retinene1) with N-bromosuccinimide, to obtain retinene2, which by reduction with lithium aluminium hydride was converted to vitamin A2.