Diastereoselective Alkylation of Carbanions Derived from 1,3-Oxathianes

Article abstract of DOI:10.1016/S0040-4039(00)77700-8

Carbanions derived from 4-substituted-1,3-oxathiolane and oxathiane were studied.The magnesium anion of 2-phenyl-4-t-butyldiphenylsilyloxy-1,3-oxathiane reacts with benzaldehyde to give the benzhydrol adduct in a seven to one ratio of diastereoisomers.It was also found that solvent had an effect on site of metalation and in ether 2-phenyl-4-dimethylamino-1,3-oxathiane reacts with s-butyllithium to give ortho metalation.The resulting anion reacts with benzaldehyde to give a 4:1 ratio of diastereoisomers. Key words: chiral carbanion; diastereoselective alkylation; ortho metalation; oxathiane.