title: Copper(I)-catalyzed enantioselective synthesis of α-chiral linear or carbocyclic (E)-(γ-alkoxyallyl)boronates.
abstract: A new method has been developed for the catalytic asymmetric synthesis of α-chiral linear or carbocyclic (γ-alkoxyallyl)boronates via the copper(I)-catalyzed γ-boryl substitution of allyl acetals. This reaction afforded the products in high yields with excellent E:Z selectivities and enantioselectivities [only (E)-product, 91-98% ee] and also exhibited high functional group compatibility. Subsequent allylation of aldehydes with the α-chiral (γ-alkoxyallyl)boronates provided the anti-1,2-diol derivatives in a highly stereospecific manner, and the utility of the α-chiral (γ-alkoxyallyl)boronates was further demonstrated by a convergent coupling of a complex polyol derivative using a (γ-alkoxyallyl)boronate and a chiral α-oxyaldehyde. The stereoselective modular construction of a complex 3,3-disubstituted cyclopentene containing three consecutive stereocenters including a quaternary chiral carbon was also reported. Useful transformations of the α-chiral linear (γ-alkoxyallyl)boronates were also demonstrated.
authors.affiliation: Division of Chemical Process Engineering & Frontier Chemistry Center, Graduate School of Engineering, Hokkaido University , Sapporo 060-8628, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Yamamoto
authors.forename: Yuta
authors.initials: Y
authors.lastname: Takenouchi
authors.forename: Taichi
authors.initials: T
authors.lastname: Ozaki
authors.forename: Takanori
authors.initials: T
authors.lastname: Miya
authors.forename: Hajime
authors.initials: H
authors.lastname: Ito