title: Palladium(0)-catalyzed alkylative cyclization of alkynals and alkynones: remarkable trans-addition of organoboronic reagents.
abstract: Palladium/monophosphine complexes catalyze trans-selective arylative, alkenylative, and alkylative cyclization reactions of alkynals and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols with endo-tri- or tetrasubstituted olefin groups and/or five-membered counterparts with exo olefin groups. The ratios of these products are dramatically affected by alkyne substituents as well as the phosphine ligand. The remarkable trans-selectivity of the process results from the novel reaction mechanism involving oxidative addition without oxametallacycle formation.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsukamoto
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Ueno
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kondo