title: TiCl4-n-Bu4NX (X = I, Br, and Cl) combination-induced coupling of alpha,beta-unsaturated ketones with aldehydes.
abstract: A three-component coupling reaction between vinyl ketones, aldehydes, and halides has been developed with TiCl(4)-n-Bu(4)NX combined reagents. Treatment of vinyl ketones with a TiCl(4)-n-Bu(4)NI combination followed by an addition of a variety of aldehydes provides syn-alpha-iodomethyl-beta-hydroxy ketones with high stereoselectivity. Methyltriphenylphosphonium iodide as well as n-Bu(4)NI acts efficiently as a halide source. The combination of TiCl(4)-n-Bu(4)NBr provides the corresponding bromo compounds in good yields. syn-alpha-Chloromethyl-beta-hydroxy ketones are obtained with the TiCl(4)-n-Bu(4)NCl combination. A competitive experiment reveals that the order of relative reactivity of the combinations is TiCl(4)-n-Bu(4)NI > TiCl(4)-n-Bu(4)NBr > TiCl(4)-n-Bu(4)NCl.
authors.affiliation: Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Z
authors.initials: Z
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Uehira
authors.forename: H
authors.initials: H
authors.lastname: Shinokubo
authors.forename: K
authors.initials: K
authors.lastname: Oshima