title: Phosphine oxide-catalyzed enantioselective intramolecular aldol reaction via regioselective enolization of unsymmetrical diketones with tetrachlorosilane.
abstract: The phosphine oxide-catalyzed asymmetric intramolecular aldol reactions of diketones were investigated. The combination of tetrachlorosilane and a chiral phosphine oxide catalyst promoted the acetyl-selective enolization of diketones, and the subsequent intramolecular aldol reaction occurred in an enantioselective manner. The introduction of two trimethylsilyl groups at the 4- and 4'-positions in BINAP dioxide catalyst improved the enantioselectivity. This reaction provides an effective synthetic method to access β-tertiary-hydroxy cyclohexanones in high yields and with high enantioselectivity.
authors.affiliation: Graduate School of Pharmaceutical Sciences and ‡Priority Organization for Innovation and Excellence, Kumamoto University , 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kotani
authors.forename: Shohei
authors.initials: S
authors.lastname: Aoki
authors.forename: Masaharu
authors.initials: M
authors.lastname: Sugiura
authors.forename: Masamichi
authors.initials: M
authors.lastname: Ogasawara
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakajima