Ph3As-catalyzed wittig-type olefination of aldehydes with diazoacetate in the presence of Na2S2O4.

In the presence of sodium hydrosulfite and a catalytic amount of AsPh3 and Fe(TCP)Cl, aldehydes react with ethyl diazoacetate to give the corresponding alpha,beta-unsaturated esters in high yields with excellent stereoselectivities (E/Z > 50/1).