[reaction: see text] High stereoselectivities (up to 98% de) have been achieved for the Lewisacid-mediated cross-coupling reaction of dimethyl acetals to a chiral 1,3-thiazolidine-2-thione-derived titanium enolate. The reaction affords enantiopure anti alpha-methyl-beta-alkoxy carbonyl compounds in a wide range of acetals.
Radical-based reduction of β-methoxy- or β-fluoro-α-bromo esters could be achieved with good stereoselection at low temperatures. A systematic evaluation of this reaction is presented and possible transition state models are discussed.