Chiral Calcium Complexes as Brønsted Base Catalysts for Asymmetric Addition of α-Amino Acid Derivatives to α,β-Unsaturated Carbonyl Compounds
作者:Susumu Saito、Tetsu Tsubogo、Shū Kobayashi
DOI:10.1021/ja0709730
日期:2007.5.1
promote the catalyticasymmetric 1,4-addition reactions and [3+2] cycloaddition reactions of α-amino acidderivatives with α,β-unsaturated carbonyl compounds have been developed. The reactions proceeded smoothly in the presence of 5−10 mol % of the chiral calcium catalyst to afford the desired adducts in high yields with high diastereo- and enantioselectivities. A wide range of α,β-unsaturated esters and
4-addition and [3 + 2] cycloaddition reactions using chiral calcium species prepared from calcium isopropoxide and chiral bisoxazoline ligands have been developed. Glycine Schiff bases reacted with acrylic esters to afford 1,4-addition products, glutamic acid derivatives, in high yields with high enantioselectivities. During the investigation of the 1,4-addition reactions, we unexpectedly found that a [3
[EN] CYCLOPROPENIMINE CATALYST COMPOSITIONS AND PROCESSES<br/>[FR] COMPOSITIONS CATALYTIQUES À BASE DE CYCLOPROPÉNIMINE ET PROCÉDÉS
申请人:UNIV COLUMBIA
公开号:WO2013059118A1
公开(公告)日:2013-04-25
The present invention provides, inter alia, a cyclopropenimine Brønsted base catalyst and a cyclopropenimine scaffold for use as a Brønsted base catalyst. This cyclopropenimine has the structure (100). Methods for making such a cyclopropenimine are also provided. Further provided are processes for carrying out an organic synthetic reaction and processes for catalyzing a proton transfer reaction enantioselectively using such a cyclopropenimine Brønsted base catalyst.
Synthesis of Glutamic Acid and Highly Functionalized Pyrrolidine Derivatives by Utilizing Tunable Calcium Catalysts for Chemoselective Asymmetric 1,4-Addition and [3+2] Cycloaddition Reactions
作者:Martin Hut'ka、Tetsu Tsubogo、Shū Kobayashi
DOI:10.1002/adsc.201300171
日期:2013.5.17
simple catalytic systems consisting of calcium chloride dihydrate, chiral ligands and tetramethylguanidine. Various Box ligands were synthesized and the most effective proved to be that bearing an indane chiral backbone and a cyano group. Depending on the structure of both glycine Schiff bases and α,β‐unsaturated compounds, the corresponding Michael adducts or pyrrolidine derivatives were obtained in
addition of glycineSchiffbases to different Michael acceptors it was found necessary to carefully optimize the reaction conditions for every single substrate class, as seemingly small structural changes sometimes required the use of totally different reaction conditions. Under carefully optimized conditions enantiomeric ratios up to 91:9 could be achieved in the addition of glycineSchiffbases to acrylates