Diastereoselective Synthesis of Tertiary α-Hydroxy Acids

Significance

This communication demonstrates the generality of the silylene transfer/sigmatropic rearrangement strategy to create highly functionalized small molecules with good stereocontrol. The original report by the same group focused on α,β-unsaturated esters (Org. Lett. 2007, 9, 1037; see also Synfacts 2007, 519). The isobutene precursor 2 gave 3 in higher yields with α-keto esters 1 than the cyclohexene silylene used previously. Retention of stereochemical information was confirmed, and even a remote stereocenter in 8 imparted acceptable levels of diastereoselectivity (dr = 9:1).