Chelation-controlled ester-derived titanium enolate aldol reaction: diastereoselective syn-aldols with mono- and bidentate aldehydes

A chelation-controlled and highly diastereoselective synthesis of syn-aldols is described. Aldol reaction of (S)-valinol-derived ester with a variety of aldehydes proceeded with high syn-diastereoselectivities (up to 99:1) and isolated yields (94%).