Best Synthetic Methods Enantioselective Oxidation and Reduction

Best Synthetic Methods Enantioselective Oxidation and Reduction 

When the substrate is readily epimerizable, as with 3, the problem is even easier. Xumu Zhang of Pennsylvania State University reports J. Am. Chem. Soc. 2004, J26, 1626) the development of achiral Ru complex (derived from C,-Tunephos) that selectively hydrogenates one of the two interconverting enantiomei S of 3, delivering 4 with high enantioseleclivity and diastereoselectivity. 

The Shaipless asymmetric dihydroxylation has played a prominent role in enantioselecitve organic synthesis. Two groups have recently reported improvements in the procedure. Osmo E.O. Horni of the University of Oulu, Finland has found (/ Org. Chem. 2004, 69, 4816) that. sodium chlorite is a more efficient reoxidant than is the usual K,[Fe(CN),]. Carlos A.M. Alfonso of the Institute Superior Tdcnico, Lisbon has reported (J. Org. Chem. 2004, 69, 4381) that the asymmetric dihydroxylation can 

Alcohol oxidation can also be enantioselective. The best systems reported to date for the selective oxidation of one enantiomer of 7 to 9 depend on the naturally-occurring alkaloid sparteine as a source of chirality. Unfortunately, only one enantiomer of sparteine is available. Peter O Brien of the University of York has developed (J. Org. Chem. 2004, 69, 5789) an alternative tricyclic amine 8 that is complementary to sparteine, directing oxidation toward R-1. 

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