Enantiocontrolled Synthesis of β‐Branched α‐Amino Acids by Using Cu
<sup>I</sup>
‐Catalyzed 1,4‐Addition of Glycine Imines to β‐Substituted
<i>gem</i>
‐Diactivated Olefins
作者:Jorge Hernández‐Toribio、Ramón Gómez Arrayás、Juan C. Carretero
DOI:10.1002/chem.201100374
日期:2011.5.27
Branching out! The catalytic asymmetric conjugate addition of glycinate Schiff bases to β‐substituted gem‐diactivated Michael acceptors under proton transfer conditions gives a variety of β‐branched α‐amino acids (see scheme; Dpm=diphenylmethylene, EWG=electron‐withdrawing group) with excellent levels of diastereo‐ (typically syn/anti >90:10) and enantiocontrol (90–99 % ee).
分支出!催化不对称共轭加成的甘氨酸Schiff碱至β -取代的宝石-diactivated质子转移条件下迈克尔受体给出的各种β-α支链氨基酸(参见方案; DPM =二苯基亚甲基,EWG =吸电子基团)具有优良的非对映体水平(通常是syn / anti > 90:10)和对映体控制(90–99% ee)。
Conjugate Addition of Perfluoroarenes to α,β-Unsaturated Carbonyls Enabled by an Alkoxide-Hydrosilane System: Implication of a Radical Pathway
reagents to α,β-unsaturated carbonyls is a key strategy for the construction of carbon-carbon bond in organic synthesis. Although direct C-H addition to unsaturated bonds via transition metal catalysis is explored in recent years, electron-deficient arenes that do not bear directing groups continue to be challenging. Herein we disclose the first example of a conjugate addition of perfluoroarenes to α,β-unsaturated
Organocatalytic enantioselective conjugate addition of nitromethane to alkylidenemalonates: asymmetric synthesis of pyrrolidine-3-carboxylic acid derivatives
作者:Saumen Hajra、Sk Mohammad Aziz、Rajat Maji
DOI:10.1039/c3ra42014k
日期:——
A highlyenantioselectivenitromethaneaddition to alkylidene malonates catalyzed by cinchona-alkaloid derived thiourea based organocatalyst has been developed that offers a new route to the synthesis of substituted pyrrolidine-3-carboxylic acid derivatives and 3-arylpyrrolidines/pyrrolidones.
Catalytic Asymmetric Conjugate Addition of a Borylalkyl Copper Complex for Chiral Organoboronate Synthesis
作者:Won Jun Jang、Jaesook Yun
DOI:10.1002/anie.201909712
日期:2019.12.9
We report the catalytic enantioselectiveconjugateaddition of a borylalkyl copper nucleophile generated in situ from a 1,1-diborylmethane derivative to α,β-unsaturated diesters. In the presence of a chiral N-heterocyclic carbene (NHC)-copper catalyst, this method facilitated the enantioselective incorporation of a CH2 Bpin moiety at the β-position of the diesters to yield β-chiral alkyl boronates
Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of Nitrones to Alkylidene Malonates: Highly Enantioselective Synthesis of Multisubstituted Isoxazolidines
All under control! A catalytic asymmetric 1,3‐dipolar cycloaddition reaction of nitrones to alkylidene malonates, catalyzed by chiral N,N′‐dioxide–Ni(ClO4)2⋅6 H2O complexes, has been developed with excellent yields, diastereo‐, and enantioselectivities (see scheme, R1=aryl, R2=alkyl, R3, R4=Ph). In addition, a possible transition state has also been proposed to elucidate the high level of enantio‐