Cooperative Catalysis of Metal and OH⋅⋅⋅O/sp3‐CH⋅⋅⋅O Two‐Point Hydrogen Bonds in Alcoholic Solvents: Cu‐Catalyzed Enantioselective Direct Alkynylation of Aldehydes with Terminal Alkynes. Issue 40 (16th August 2013)

• Record Type: Journal Article
• Authors: Ishii, Takaoki; Watanabe, Ryo; Moriya, Toshimitsu; Ohmiya, Hirohisa; Mori, Seiji; Sawamura, Masaya
• Is Part Of: Chemistry. Volume 19:Issue 40(2013)
• Page Start: 13547
• Page End: 13553
• Publication Date: 2013-08-16
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201301280
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Catalyst–substrate hydrogen bonds in artificial catalysts usually occur in aprotic solvents, but not in protic solvents, in contrast to enzymatic catalysis. We report a case in which ligand–substrate hydrogen‐bonding interactions cooperate with a transition‐metal center in alcoholic solvents for enantioselective catalysis. Copper(I) complexes with prolinol‐based hydroxy amino phosphane chiral ligands catalytically promoted the direct alkynylation of aldehydes with terminal alkynes in alcoholic solvents to afford nonracemic secondary propargylic alcohols with high enantioselectivities. Quantum‐mechanical calculations of enantiodiscriminating transition states show the occurrence of a nonclassical sp³‐CH⋅⋅⋅O hydrogen bond as a secondary interaction between the ligand and substrate, which results in highly directional catalyst–substrate two‐point hydrogen bonding.</p> </abstract>