The reaction of C, O, O-tris (trimethylsilyl) ketene acetal 1 with saturated, cyclic and aromatic ketones 2 proceeds smoothly in the presence of titanium chloride to give (E)-α, β- unsaturated carboxylic acids 3 with fairly good stereoselectivity. With α, β-unsaturated ketones 4, α-trimethylsilyl δ-ketoacids 5 (syn+ anti) are obtained according to Michael-type 1, 4 addition. These diastereoisomers are separated and the configurations of 5a are ...
[Fujisawa, Tamotsu; Sato, Toshio; Gotoh, Yoshihiko; Kawashima, Masatoshi; Kawara, Tatsuo Bulletin of the Chemical Society of Japan, 1982 , vol. 55, # 11 p. 3555 - 3559]