作者:Ashok K. Basak、Naoyuki Shimada、William F. Bow、David A. Vicic、Marcus A. Tius
DOI:10.1021/ja103028r
日期:2010.6.23
An organocatalytic asymmetric Nazarov cyclization of diketoesters that proceeds by means of a dual activation mechanism has been developed. Screening of a number of catalysts led to a new thiourea that incorporates a primary amino group. The method gives rise to cyclic products with two adjacent quaternaryasymmetriccarbon atoms, one of which is an all-carbon stereocenter, with complete or nearly
Enantioconvergent Cross-Couplings of Racemic Alkylmetal Reagents with Unactivated Secondary Alkyl Electrophiles: Catalytic Asymmetric Negishi α-Alkylations of <i>N</i>-Boc-pyrrolidine
作者:Christopher J. Cordier、Rylan J. Lundgren、Gregory C. Fu
DOI:10.1021/ja4054114
日期:2013.7.31
Although enantioconvergent alkyl-alkyl couplings of racemic electrophiles have been developed, there have been no reports of the corresponding reactions of racemic nucleophiles. Herein we describe Negishicross-couplings of racemic α-zincated N-Boc-pyrrolidine with unactivated secondary halides, thus providing a one-pot, catalytic asymmetric method for the synthesis of a range of 2-alkylpyrrolidines
With the aid of a class of newly discovered Trost-type bisphosphine ligands bearing a chiral cycloalkane framework, the Pd-catalyzed decarboxylative dearomative asymmetric allylic alkylation (AAA) of benzofurans was achieved with high efficiency [0.2-1.0 mol% Pd2(dba)3/L], good generality and high enantioselectivity (> 30 examples, 82-99% yield and 90-96% ee). Moreover, a diversity-oriented synthesis
We herein report a general, practical, and highly efficient method for asymmetricsynthesis of a wide range of chiral vicinal diamines via reductive coupling of imines templated by chiral diboron. The protocol features high enantioselectivity and stereospecificity, mild reaction conditions, simple operating procedures, use of readily available starting materials, and a broad substrate scope. The method
Synthesis of Phosphoramides for the Lewis Base-Catalyzed Allylation and Aldol Addition Reactions
作者:Scott E. Denmark、Xiping Su、Yutaka Nishigaichi、Diane M. Coe、Ken-Tsung Wong、Stephen B. D. Winter、Jun Young Choi
DOI:10.1021/jo9820723
日期:1999.3.1
Both chiral and achiral phosphoramides of diverse structure were prepared from diamines by the coupling to phosphorus(V) or phosphorus(III) reagents. Several enantiopure 1,2-diphenyl-1,2-ethanediamine analogues have been prepared by the reductive coupling of the corresponding N-silylimine with NbCl(4)(THF)(2) and subsequent resolution by the formation of diastereomeric menthyl carbamates. (S,S)-N,