Enantioselective aldol reaction with bromofluoroketene silyl acetals

✍ Scribed by Katsuhiko Iseki; Yoshichika Kuroki; Yoshiro Kobayashi

• Book ID: 104209225
• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 812 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00005-8

✦ Synopsis

The aldol reaction of aldehydes with bromofluoroketene ethyl trimethylsilyl acetal in the presence of a catalytic amount of a ehiral Lewis acid at -780C provides a mixture of the corresponding synand anti-o~-bromo-o~-fluoro-~-hydroxy esters with high enantioselectivities (up to 99% ee).

Reaction temperature has a great influence on the stereoselectivity. The aldol reaction at -20"C proceeds with high enantio-and diastereoselectivities to preferentially afford the anti-aldols having opposite signs of optical rotation to those at -780C.