PNAS 2004-04-13

Asymmetric hetero-Diels-Alder reaction catalyzed by dirhodium(II) carboxamidates.

Michael P Doyle, Marcela Valenzuela, Penglin Huang

Index: Proc. Natl. Acad. Sci. U. S. A. 101(15) , 5391-5, (2004)

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Abstract

Chiral dirhodium(II) carboxamidates are highly efficient catalysts for reactions between a variety of aldehydes and activated dienes. Catalyst loadings as low at 0.01 mol % have been realized with enantioselectivities up to 97%. Kinetic investigations reveal a pronounced electronic influence on the rate of the hetero-Diels-Alder reaction with a Hammett rho value of +1.9 (versus sigma(+)). Inhibition of the catalyst by reactant aldehyde is apparent, but reactions show first-order dependence on aldehyde and diene, and there is a variable dependence on catalyst.