title: Copper-catalyzed enantioselective allylic alkylation of terminal alkyne pronucleophiles.
abstract: The copper-catalyzed enantioselective allylic alkylation of terminal alkynes with primary allylic phosphates was developed by the use of a new chiral N-heterocyclic carbene ligand bearing a phenolic hydroxy group at the ortho position of one of the two N-aryl groups. This reaction occurred with excellent γ-branch regioselectivity and high enantioselectivity, forming a controlled stereogenic center at the allylic/propargylic position. Various terminal alkynes, including silyl, aliphatic, and aromatic alkynes, could be used directly without premetalation of the C(sp)-H bond. On the basis of the results of experiments using an isomeric secondary allylic phosphate, which gave a branched product through an α-selective substitution reaction with retention of configuration, a reaction pathway involving 1,3-allylic migration of Cu in a ([σ + π]-allyl)copper(III) species is proposed.
authors.affiliation: Department of Chemistry, Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Harada
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Makida
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Sato
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Ohmiya
authors.forename: Masaya
authors.initials: M
authors.lastname: Sawamura