Enantioselective synthesis of nitroalkanes bearing all-carbon quaternary stereogenic centers through Cu-catalyzed asymmetric conjugate additions

The first examples of catalytic asymmetric conjugate addition (ACA) of alkylzinc reagents to trisubstituted nitroalkenes, leading to the formation of nitroalkanes bearing a quaternary carbon stereogenic center, are reported. Reactions are promoted in the presence of 4 mol % of a readily available amino acid-based phosphine and 2 mol % (CuOTf)·C6H6. Cu-catalyzed reactions proceed efficiently in up to 98% ee and can be carried out with a variety of dialkylzinc reagents and trisubstituted nitroolefins. We highlight the synthetic utility of the products obtained by efficient conversion of optically enriched nitroalkanes to the corresponding carboxylic acids. Copyright © 2005 American Chemical Society.