Chiral spiroaminoborate ester as a highly enantioselective and efficient catalyst for the borane reduction of furyl, thiophene, chroman, and thiochroman-containing ketones
摘要:
Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were successfully reduced in the presence of 1-10 mol% of spiroaminoborate ester 1 with different borane sources to afford non-racemic alcohols in up to 99% ee. In addition, modest enantioselectivity, around 80% ee, was achieved in the reduction of linear alpha,beta-unsaturated heteroaryl ketones. (C) 2009 Elsevier Ltd. All rights reserved.
Copper-Catalyzed Enantioselective Conjugate Addition of Grignard Reagents to Acyclic Enones
作者:Fernando López、Syuzanna R. Harutyunyan、Adriaan J. Minnaard、Ben L. Feringa
DOI:10.1021/ja046632t
日期:2004.10.1
A highly enantioselective Cu-catalyzed addition of Grignard reagents to acyclic aliphatic enones is described. In the presence of 5 mol % of CuBr.SMe2 and 6 mol % of JosiPhos diphosphine aliphatic enones react with Grignard reagents to provide beta-substituted linear ketones with high yields, regio-, and enantioselectivities.
On the Mechanism of the Copper-Catalyzed Enantioselective 1,4-Addition of Grignard Reagents to α,β-Unsaturated Carbonyl Compounds
作者:Syuzanna R. Harutyunyan、Fernando López、Wesley R. Browne、Arkaitz Correa、Diego Peña、Ramon Badorrey、Auke Meetsma、Adriaan J. Minnaard、Ben L. Feringa
DOI:10.1021/ja0585634
日期:2006.7.19
The mechanism of the enantioselective 1,4-addition of Grignardreagents to alpha,beta-unsaturated carbonyl compounds promoted by copper complexes of chiral ferrocenyl diphosphines is explored through kinetic, spectroscopic, and electrochemical analysis. On the basis of these studies, a structure of the active catalyst is proposed. The roles of the solvent, copper halide, and the Grignardreagent have
Wittig Reactions of Stabilized Phosphorus Ylides with Aldehydes in Water
作者:Jinlong Wu、Da Zhang、Shaoyong Wei
DOI:10.1081/scc-200054816
日期:2005.5
Abstract The Wittigreactions of three stabilized phosphorus ylides with aldehydes in water were investigated. Most of the olefination reactions completed within 5–60 min in refluxing water in the presence of 1.2 M LiCl to afford the olefin products in 65–98% yields. It was found that the Wittigreactions of stabilized phosphorus ylides with aldehydes in water were faster than those carried out in
Cobalt-Mediated [3 + 2]-Annulation Reaction of Alkenes with α,β-Unsaturated Ketones and Imines
作者:Jennifer M. Schomaker、F. Dean Toste、Robert G. Bergman
DOI:10.1021/ol901542n
日期:2009.8.20
adducts with conjugate acceptors in the presence of Sc(OTf)3/LHMDS formed two new C−C bonds at the carbons α to the nitrosyl groups of the substrate, leading to unusual tri- and tetracycles. Retrocycloaddition of these products in the presence of norbornadiene yielded functionalized tetrasubstituted bicyclic olefins.
Cobalt Dinitrosoalkane Complexes in the C−H Functionalization of Olefins
作者:Jennifer M. Schomaker、W. Christopher Boyd、Ian C. Stewart、F. Dean Toste、Robert G. Bergman
DOI:10.1021/ja800738d
日期:2008.3.1
The use of cobalt dinitrosoalkane complexes in the C-H functionalization of alkenes has been demonstrated. Reaction of a series of alkenes with Me(4)CpCo(CO)(2) in the presence of NO generates intermediate cobalt dinitrosoalkane complexes that can be deprotonated M to the nitrosyl group and added to various Michael acceptors. The resultant products can then undergo retrocycloaddition reactions in the presence of the original alkene to regenerate the starting cobalt dinitrosoalkane complex and release the functionalized alkene.