Selective Reductions

The Lewis acidity of CeCl₃ plays important role with metal hydrides in the reduction of carbonyl compounds. The combination of NaBH₄ and CeCl₃·7H₂O is used for the selective reduction of carbonyl compounds. The reaction is called Luche Reduction. For examples, the stereochemistry can be reversed in the reduction of bicyclic ketone using NaBH₄ -CeCl₃ (Scheme 18-19).

L. A. Paquette, Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons, Inc., L. A. Paquette, Ed., New York, 1995, 2 , 1031.

Scheme 18

Scheme 19

 

The above described reagent can also be used for the chemoselective reduction of ketones in the presence of aldehyde functional group (Scheme 20).

 

Scheme 20

Examples:

J. I. Luche, J. Am. Chem. Soc. 1978 , 100 , 2226.

 

L. A. Paquette, D. T. Belmont, Y.-L. Hsu, J. Org. Chem. 1985 , 50 , 4667.