title: Direct catalytic asymmetric aldol-Tishchenko reaction.
abstract: A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Vijay
authors.initials: V
authors.lastname: Gnanadesikan
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Horiuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohshima
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Shibasaki