Asymmetric Reductive Coupling of 1,3-Enynes to Glyoxalates
Y.-T. Hong, C.-W. Cho, E. Skucas, M. J. Krische*
University of Texas at Austin, USA and Kyungpook National University, Daegu, Korea
22. November 2007 (online)
In an earlier work the Krische lab has reported the coupling of 1,3-diynes to glyoxolates (C.-W. Cho, M. J. Krische Org. Lett. 2006, 8, 3873). The present study demonstrates the reductive coupling of 1,3-enynes to glyoxolates catalyzed by a cationic rhodium catalyst modified by ligand 1. Interestingly, commercially available chelating chiral phosphine ligands were uniformly unable to provide high levels of asymmetric induction. Lastly, the hydroxyl ester coupling products are elaborated to provide various useful chiral building blocks.