title: Quick installation of a 1,4-difunctionality via regioselective nickel-catalyzed reductive coupling of ynoates and aldehydes.
abstract: The development of efficient methods for the synthesis of molecules with 1,4-difunctionalities has been a dire need of the synthetic community. In this work, intermolecular reductive coupling of ynoates and aldehydes (in the presence of a silane) has been accomplished for the first time using catalytic amounts of Ni(COD)(2), an N-heterocyclic carbene ligand, and PPh(3). High regioselectivity has been demonstrated for the multicomponent coupling reactions, and more than a dozen invaluable silyl-protected γ-hydroxy-α,β-enoates have been synthesized. This methodology provides a quick entry to many other 1,4-difunctional compounds and oxygen-containing five-membered rings. The intermediacy of metallacycles in the catalytic process has been established by deuterium-labeling experiments.
authors.affiliation: Department of Chemistry, University of Cincinnati, P.O. Box 21072, Cincinnati, Ohio 45221-0172, USA.
authors.forename: Sanjeewa K
authors.initials: SK
authors.lastname: Rodrigo
authors.forename: Hairong
authors.initials: H
authors.lastname: Guan