Stereoselective reactions of lithio-vinylsulf oxides with aldehydes

Abstract

A series of homochiral vinyl sulfoxides—synthesised by treating vinyl Grignard reagents with homochiral menthyl toluene-p-sulfinate or sulfinyl oxazolidinones 8a and 9a–were deprotonated with LDA and allowed to react with acetaldehyde, isobutyraldehyde, and trimethylacetaldehyde to give β-hydroxy sulfoxides with moderate diastereoselectivity. The sulfoxide 1 gave the best selectivity with the larger aldehyde. The same diastereoselectivity, within experimental error, is observed in the reactions with trimethylacetaldehyde of both E-1 and Z-1 giving 85:15 and 84:16 mixtures of 2c and 3c respectively; evidently, the geometry of the vinyl group does not affect the selectivity.