title: Forming Stereogenic Centers in Acyclic Systems from Alkynes.
abstract: The combined carbometalation/zinc homologation followed by reactions with α-heterosubstituted aldehydes and imines proceed through a chair-like transition structure with the substituent of the incoming aldehyde residue preferentially occupying a pseudo-axial position to avoid the two gauche interactions. The heteroatom in the axial position produces a chelated intermediate (and not a Cornforth-Evans transition structure for α-chloro aldehydes and imines) leading to a face differentiation in the allylation reaction. This method provides access to functionalized products in which three new carbon-carbon bonds and two to three stereogenic centers, including a quaternary one, were created in acyclic systems in a single-pot operation from simple alkynes.
authors.affiliation: The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry and Lise Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 (Israel).
authors.forename: Roxane
authors.initials: R
authors.lastname: Vabre
authors.affiliation: The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry and Lise Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 (Israel).
authors.forename: Biana
authors.initials: B
authors.lastname: Island
authors.affiliation: Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, 35392 Giessen (Germany).
authors.forename: Claudia J
authors.initials: CJ
authors.lastname: Diehl
authors.affiliation: Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, 35392 Giessen (Germany).
authors.forename: Peter R
authors.initials: PR
authors.lastname: Schreiner
authors.affiliation: The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry and Lise Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa 32000 (Israel). chilanm@tx.technion.ac.il.
authors.forename: Ilan
authors.initials: I
authors.lastname: Marek
keywords: acyclic stereoselection; allylation; chelation; quaternary carbon center; zinc carbenoids