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 α,β-unsaturated esters in high yields with excellent stereoselectivities (E/Z > 50/1).