Synfacts 2010(5): 0601-0601  
DOI: 10.1055/s-0029-1219750
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Asymmetric Povarov Reactions Cobalt-Catalyzed by Chiral Ureas/Achiral Acids

Contributor(s): Benjamin List, Ji-Woong Lee
H. Xu, S. J. Zuend, M. G. Woll, Y. Tao, E. N. Jacobsen*
Harvard University, Cambridge, USA
Further Information

Publication History

Publication Date:
22 April 2010 (online)

Significance

Jacobsen and co-workers report an asymmetric [4+2] cycloaddition of imines 2 with electron-rich alkenes (Povarov reaction) catalyzed by chiral urea-sulfinamide catalyst 1 and ortho-nitrobenzenesulfonic acid ­(NBSA) as an achiral co-catalyst. Detailed kinetic and computational studies strongly supported a cationic reaction intermediate. Cooperative catalysis of a chiral urea and an achiral Brønsted acid rendered a broad substrate scope with reasonable yield, dia­stereoselectivity, and high enantioselectivity. In particular, glyoxylate ester derived imines generated tetrahydroquinolines which are useful in the synthesis of a variety of natural products, such as martinelline.