Bis(trimethylsilyloxy)alkenes from the modified acyloin reaction of Schräpler and Rühlmann; stereochemical considerations

Abstract

The acyloin condensation of ethyl acetate brought about by sodium–ether–chloro(trimethyl)silane gave the Z-and E-isomers of 2,3-bis(trimethylsilyloxy)but-2-ene, (IV) and (V), in the ratio 9 : 1. Stereochemical assignments are based on spectroscopic data and correlation with the diastereoisomeric butane-2,3-diols via hydrogenation. Use of dichloro(dimethyl)silane in the acyloin reaction in place of chloro(trimethyl)silane led to formation of 2,3-bis(ethoxytrimethylsilyloxy)but-2-ene (IX).