Novel organic catalysts for the direct enantioselective α-oxidation of carbonyl compounds

The proline-derived N-sulfonylcarboxamide-catalyzed direct enantioselective alpha-oxidation of ketones and aldehydes with nitrosobenzene is presented. The reactions proceed smoothly furnishing the corresponding alpha-aminoxylated compounds in good yields with up to > 99% ee. The proline-derived N-sulfonylcarboxamides were also found to be excellent catalysts for the direct enantioselective nitroso Diels-Alder-type reaction between nitrosobenzene and of alpha,beta-unsaturated cyclic ketones yielding the corresponding bicyclic Diels-Alder adduct products with tip to > 99% ee. The proline-derived N-sulfonylcarboxamides represent a readily available and highly modular novel type of organic catalyst. (c) 2005 Elsevier Ltd. All rights reservesd.