The present invention relates to a process for stereoselective cycloaddition reactions which generally comprises a cycloaddition reaction between a pair of substrates, each either chiral or prochiral, that contain reactive &pgr;-systems, in the presence of a non-racemic chiral catalyst, to produce a stereoisomerically enriched product. The present invention also relates to novel asymmetric catalyst complexes comprising a metal and an asymmetric tridentate ligand.
Various heterogeneously or homogeneously hybridized salen/salan ligands were synthesized, and study of hetero Diels–Alder reactions using their chromium complexes as catalysts revealed that a well-designed heterogeneously hybridized ligand serves as a chiral auxiliary as efficiently as the homogeneously hybridized ligand and its chromium complex has high catalytic activity.
Asymmetric Hetero Diels-Alder Reaction Catalyzed by Chiral Ytterbium(III) Phosphate{Yb[(<i>R</i>)-(-)-BNP]<sub>3</sub>}: Remarkable Ligand Effect on the Enantioselectivity
作者:T. Hanamoto、H. Furuno、Y. Sugimoto、J. Inanaga
DOI:10.1055/s-1997-718
日期:——
2,6-Lutidine was found to be an effective additive for the chiral ytterbium(III) phosphate Yb[(R)-(-)-BNP]3}-catalyzed asymmetric hetero Diels-Alder reaction thus achieving high enantioselectivity (up to 93% ee) at room temperature.
DIANANE-CrIII-salen Complexes as Highly Enantioselective Catalysts for Hetero-Diels–Alder Reactions of Aldehydes with Dienes
作者:Albrecht Berkessel、Nadine Vogl
DOI:10.1002/ejoc.200600359
日期:2006.11
applied to the hetero-Diels–Alderreaction of Danishefsky’s diene with various aldehydes. The reactions afford the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-ones in high yields and enantioselectivities (up to 96 % ee). The effect of different counteranions of the complex on reactivity as well as enantioselectivity has been investigated. Besides Danishefsky’s diene, reaction of the less reactive
Methods of performing cycloadditions, reaction mixtures, and methods of performing asymmetric catalytic reactions
申请人:The University of Chicago
公开号:US07230125B1
公开(公告)日:2007-06-12
Methods of performing cycloadditions are described that include (a) combining a first reactant and a second reactant in a hydrogen bonding solvent to form a reaction mixture; and (b) reacting the first reactant and the second reactant to form a cycloadduct. Methods of performing asymmetric catalytic reactions are also described that include (a) combining a first reactant, a second reactant, and a catalytic amount of a chiral hydrogen-bond donor in a solvent to form a reaction mixture; and (b) reacting the first reactant and the second reactant to form an enantiomeric excess of a reaction product. Reaction mixtures corresponding to these methods are also described.