[Ph.sub.3]As-catalyzed Wittig-type olefination of aldehydes with diazoacetate in the presence of [Na.sub.2][S.sub.2][O.sub.4]

Aldehydes have reacted with ethyl diazoacetate in the presence of sodium hydrosulfite and a catalytic amount of As[Ph.sub.3] and Fe(TCP)Cl in order to give the corresponding [alpha],[beta]-unsaturated esters. The high yield, stereoselectivity, use of catalytic amount of As[Ph.sub.3] and cheap inorganic reducing agent has made this method practically useful for the synthesis of [alpha],[beta]-unsaturated esters.