Palladium(0)-catalyzed alkylative cyclization of alkynals and alkynones: remarkable trans-addition of organoboronic reagents.
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.
Tsukamoto
Hirokazu
H
Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan.
Ueno
Tatsuhiko
T
Kondo
Yoshinori
Y