Enamines of 2,2-bis(ethylthio)ethanal: a convenient route to γ-keto crotonate derivatives

Abstract

A new α-oxoaldehyde reagent, 2,2-bis(ethylthio)ethanal 1, has been prepared in high yield from ethanedial. Alkylation of the potassium salt of the enamines of 1 with various alkylating agents followed by insitu hydrolysis of the intermediate imine afforded high yields of the alkylation products of 1. This new reagent was used in the synthesis of a chiral potential precursor of the macrocyclic fragment of cytochalasins A, B, and F, as well as in the syntheses of the physiologically active diolides pyrenophorin and norpyrenophorin.