Hetero-Diels-Alder reactions of ketones - A challenge for chemists

Abstract

The recent developments of mainly catalytic and enantioselective hetero-Diels-Alder reactions of ketones are presented. First, direct reactions of unactivated ketones are presented, focusing on the recent hydrogen bond-promoted hetero-Diels-Alder reactions with activated conjugated dienes. Then, direct catalytic enantioselective hetero-Diels-Alder reactions of activated ketones with conjugated dienes are outlined. The use of different chiral copper(II) and zinc(II) catalysts are shown and the use of the hetero-Diels-Alder adducts in organic synthesis presented. Finally, the inverse-electron demand hetero-Diels-Alder reactions of α,β- unsaturated ketone functionalities are discussed. The different chiral Lewis-acid complexes and chiral amines used for catalytic asymmetric hetero-Diels-Alder reactions are presented and the scope of these reactions in the synthesis of optically active α-hydroxy lactones, formyl esters and carbohydrates are demonstrated. The mechanistic aspects of the catalytic enantioselective hetero-Diels-Alder reactions are also discussed. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.