Highly stereoselective TiCl4-Catalyzed Evans-aldol and Et3Al-mediated Reformatsky reactions. Efficient accesses to optically active syn- or anti-alpha-trifluoromethyl-beta-hydroxy carboxylic acid derivatives.
[reaction: see text] The TiCl(4)-catalyzed Evans-aldol reaction of optically active 3,3,3-trifluoropropanoic imide gave the non-Evans syn product stereoselectively, whereas the Reformatsky reaction of 2-bromo-3,3,3-trifluoropropanoic imide in the presence of Et(3)Al led to the Evans anti product. These new approaches enabled us to synthesize all stereoisomers of trifluoromethylated aldol products for the first time.
Shimada
Taichi
T
Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Yoshioka
Masamitsu
M
Konno
Tsutomu
T
Ishihara
Takashi
T