title: Reversible 1,3-anti/syn-stereochemical courses in copper-catalyzed γ-selective allyl-alkyl coupling between chiral allylic phosphates and alkylboranes.
abstract: The stereochemical courses of the copper-catalyzed allyl-alkyl coupling between enantioenriched chiral allylic phosphates and alkylboranes were switchable between 1,3-anti and 1,3-syn selectivities by the choice of solvents and achiral alkoxide bases with different steric demands. The reactions with γ-silylated allylic phosphates allow efficient synthesis of enantioenriched chiral allylsilanes with tertiary or quaternary carbon stereogenic centers. Cyclic and acyclic bimodal participation of alkoxyborane species in an organocopper addition-elimination sequence is proposed to account for the phenomenon of the anti/syn-stereochemical reversal.
authors.affiliation: Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nagao
authors.forename: Umi
authors.initials: U
authors.lastname: Yokobori
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Makida
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Ohmiya
authors.forename: Masaya
authors.initials: M
authors.lastname: Sawamura