Catalytic applications of chiral organoselenium compounds in asymmetric synthesis

Chiral selenium-containing compounds have found growing application in asymmetric catalysis over the past few years. The large majority of these ligands are derived from readily available chiral amino alcohols in a few high-yielding synthetic steps. The advantages of using these compounds are described, particularly those regarding ready accessibility, modular nature, formation of strong bonds with soft metals and more rarely with hard ones. By using an appropriate electrophilic or nucleophilic organoselenium fragment, novel chiral organoselenium catalysts or ligands were designed from chiral aziridines, oxazolines, ferrocenes, etc. High regioselectivity and enantioselectivity were achieved through the four following techniques: the enantioselective copper-catalyzed conjugate addition of organometallic reagents to enones, the diorganozinc addition to aldehydes, palladium-catalyzed enantioselective allylic alkylation and asymmetric hydrosilylation or transfer hydro-genations of ketones. 1 Introduction 2 Chiral Organoselenium Compounds as Catalysts for Enantioselective Synthesis 2.1 Enantioselective Hydrosilylation of Ketones 2.2 Enantioselective Addition of Diorganozinc Reagents to Aldehydes 2.3 Enantioselective Conjugate Additions to Enones 2.4 Palladium-Catalyzed Asymmetric Allylic Alkylations 3 Summary and Outlook