Reaction of alkyl vinyl ethers with d-galactose diethyl dithioacetal

Abstract

d-Galactose diethyl dithioacetal was brought into reaction, under acid catalysis, with each of several alkyl vinyl ethers in equimolar quantities. The major reaction product, 5,6- O-ethylidene- d-galactose diethyl dithioacetal, was isolated and its structure was proved by reductive desulfurization with subsequent periodate oxidation. This structure was confirmed by mass spectral data. When ethyl vinyl ether was used, the minor reaction-product was 6- O-(1-ethoxyethyl)- d-galactose diethyl dithioacetal. A pathway is proposed for this reaction. 5,6- O-Ethylidene- d-galactose diethyl acetal was partially demercaptalated to ethyl 5,6- O-ethylidene-1-thio-α- d-galactofuranoside, whose structure was confirmed through its synthesis by the reaction of isopropyl vinyl ether with ethyl 1-thio-α- d-galatofuranoside under acid catalysis.