Enantioselective Reductive Coupling of 1,3-Enynes to Glyoxalates Mediated by Hydrogen: Asymmetric Synthesis of β,γ-Unsaturated α-Hydroxy Esters
Young-Taek Hong, Chang-Woo Cho, Eduardas Skucas and Michael J. Krische*
*Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, Email: mkrischemail.utexas.edu
Y.-T. Hong, C.-W. Cho, E. Skucas, M. J. Krische, Org. Lett., 2007, 9, 3745-3748.
Catalytic hydrogenation of 1,3-enynes in the presence of ethyl glyoxalate at ambient pressure and temperature using a rhodium catalyst modified by (R)-(3,5-tBu-4-MeOPh)-MeO-BIPHEP results in highly regio- and enantioselective reductive coupling to furnish the corresponding α-hydroxy esters.
see article for more examples
Highly Enantioselective Direct Reductive Coupling of Conjugated Alkynes and α-Ketoesters via Rhodium-Catalyzed Asymmetric Hydrogenation
J.-R. Kong, M.-Y. Ngai, M. J. Krische, J. Am. Chem. Soc., 2006, 128, 718-719.
1,3-Dienes, Allylic Alcohols, Hydrogen, 1,3-Enynes