title: Alpha-hydroxy esters via enantioselective hydrogen-mediated C-C coupling: regiocontrolled reactions of silyl-substituted 1,3-diynes.
abstract: [reaction: see text] Catalytic hydrogenation of ethyl glyoxalate in the presence of 1,3-diynes 4a-9a using chirally modified rhodium catalysts enables formation of alpha-hydroxy esters 4c-9c in highly optically enriched form. Notably, for such trialkylsilyl-substituted 1,3-diynes, C-C coupling occurs exclusively at the carbon atom bearing silicon. Pi-back-bonding from low valent rhodium as described by the Dewar-Chatt-Duncanson model appears to direct the regiochemistry of C-C coupling, as corroborated by calculations of the diyne LUMO coefficients.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Chang-Woo
authors.initials: CW
authors.lastname: Cho
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Krische
mesh_terms: D002384:Catalysis; D053280:Diynes / Q000737:chemistry*; D004952:Esters; D006865:Hydrogenation; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D053280:Diynes; D004952:Esters; D012821:Silanes; D012238:Rhodium