Luche Reduction

The selective 1,2-reduction of enones with sodium borohydride is achieved in combination with CeCl₃.

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Mechanism

CeCl₃ is a selective Lewis acid catalyst for the methanolysis of sodium borohydride. The resulting reagents, various sodium methoxyborohydrides, are harder reducing agents (according to HSAB principles) and therefore effect an 1,2-reduction with higher selectivity.

Furthermore, CeCl₃ activates methanol.

 

Recent Literature

Reduction of ketones to alcohols using a decaborane/pyrrolidine/cerium(III) chloride system in methanol
J. W. Bae, S. H. Lee, Y. J. Jung, C.-O. M. Yoon, C. M. Yoon, Tetrahedron Lett., 2001, 42, 2137-2139.

A Facile Approach to the Synthesis of Allylic Spiro Ethers and Lactones
M.-C. P. Yeh, Y.-C. Lee, T.-C. Young, Synthesis, 2006, 3621-3624.