Synthesis and desilylation of (2R,3S)-alpha-methyl-alpha-silyl-alpha,beta-2,3-dihydroxycarboxylic methyl esters

Addition reactions of the chiral lithium (2S)-enolates of the (2S,5S)-2-tert-butyl-5,-methyl-[1,3]dioxolan-4-one and (2S,5S)-2-tert-butyl-2,5-dimethyl-[1,3]dioxolan-4-one with linear aliphatic acylsilanes yield the corresponding (2S,5R,1'R)-1'-trimethylsilyl-dioxolanone alcohols. Sodium methoxide-induced removal of the acetal center at C-2 affords the corresponding methyl (2R,3R)-2,3-dihydroxy-2-methyl-3-trimethylsilyl alkanoates. The desilylation of these esters occurs with complete retention of configuration yielding the corresponding (2R,3S)-2,3-dihydroxy-2-methyl-alkanoic acids