title: Carbon acid induced Mukaiyama aldol type reaction of sterically hindered ketones.
abstract: 1,1,3,3-Tetrakis(trifluoromethanesulfonyl)propane (Tf(2)CHCH(2)CHTf(2)) is one of the most effective Brønsted acid precatalysts for the Mukaiyama aldol type reactions of sterically hindered ketones. By using Tf(2)CHCH(2)CHTf(2) in a range from 0.5 to 2.0 mol %, the vinylogous Mukaiyama aldol reaction of alpha-substituted cyclohexanones with 2-silyloxyfurans smoothly proceeded to give the aldol products in excellent yield without the loss of diastereoselectivity. Under similar conditions, acyclic ketene silyl acetals also performed as nice nucleophiles toward sterically hindered ketones. These findings suggest that Tf(2)CHCH(2)CHTf(2) induced Mukaiyama aldol type reactions can overcome the steric hindrance between reaction sites.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Yanai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshino
authors.forename: Arata
authors.initials: A
authors.lastname: Takahashi
authors.forename: Takeo
authors.initials: T
authors.lastname: Taguchi
mesh_terms: D000143:Acids / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000143:Acids; D000447:Aldehydes; D007659:Ketones; D002244:Carbon; C116609:3-hydroxybutanal