Homo- and heterogeneous organocatalysis: enantioselective Mannich addition of ketones to endocyclic carbon-nitrogen double bonds

The proline-catalyzed Mannich addition of ketones to chalkogenazines is reported. Yields and enantioselectivities of the corresponding products were good to excellent, using different types of organocatalysts. Furthermore the immobilization of hydroxyproline into a readily synthesized polystyrene-copolymer was accomplished. The catalytic performance of this heterogeneous catalyst was successfully demonstrated in the discussed Mannich reaction. (C) 2010 Elsevier Ltd. All rights reserved.