The synthesis of aracemic 4-substituted pyrrolidinones and 3-substituted pyrrolidines. An asymmetric synthesis of (-)-rolipram
摘要:
Conjugate additions of RCuCNLi to the chiral alpha,beta-unsaturated lactam 4 gives almost exclusive exo addition-a reversal in stereochemistry when cuprates were added to chiral lactam 1. The lactams 5 were transformed into 4-substituted pyrrolidinones 8 via a three-step sequence which involved decarbalkoxylation, silane reduction and metal-ammonia benzylamine cleavage. The chemical yields as well as the enantiomeric purity were very high for this process. As an example of the usefulness of this scheme, the antidepressant (-)-Rolipram was prepared in good overall yield. Furthermore, the bicyclic lactams 6 were readily transformed, using alane as the reducing agent, to 3-substituted pyrrolidines 11. Absolute configurations of 8 and 11 were confirmed by comparison with literature assignments which also gave strong support to the facial addition of the cuprates to 4.
Enantioselective Radical Cyclization for Construction of 5-Membered Ring Structures by Metalloradical C–H Alkylation
作者:Yong Wang、Xin Wen、Xin Cui、X. Peter Zhang
DOI:10.1021/jacs.8b01662
日期:2018.4.11
use of unsaturated substrates. Guided by the concept of metalloradicalcatalysis, a different mode of radical cyclization that can employ saturated C-H substrates is demonstrated through the development of a Co(II)-based system for catalytic activation of aliphatic diazo compounds for enantioselective radical alkylation of various C(sp3)-H bonds. It allows for efficient construction of chiral pyrrolidines
自由基环化代表了构建环状结构的强大策略。传统的自由基环化以自由基加成为关键步骤,需要使用不饱和底物。在金属自由基催化概念的指导下,通过开发基于Co(II)的系统,展示了一种可以使用饱和CH底物的不同自由基环化模式,该系统用于催化活化脂肪族重氮化合物,以实现各种C(sp3)的对映选择性自由基烷基化)-H键。它可以有效构建手性吡咯烷和其他有价值的五元环状化合物。这种自由基环化的替代策略提供了一种新的逆合成范例,通过 CH 和 C=O 元素的结合形成 CC 键,从容易获得的开链醛制备五元环状分子。
Process for the preparation of enantiomerically enriched cyclic beta-aryl or heteroaryl carbocyclic acids
申请人:Bachmann Stephan
公开号:US20070232653A1
公开(公告)日:2007-10-04
The present invention relates to a process for the preparation of cis substituted cyclic β-aryl or heteroaryl carboxylic acid derivatives in high diastereo- and enantioselectivity by enantioselective hydrogenation in accordance with the following scheme
wherein
X, Ar, n, and m are defined herein and corresponding salts thereof.
PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY ENRICHED CYCLIC BETA-ARYL OR HETEROARYLCARBOCYCLIC ACIDS
申请人:Bachmann Stephan
公开号:US20110105758A1
公开(公告)日:2011-05-05
The present invention relates to a process for the preparation of cis substituted cyclic β-aryl or heteroaryl carboxylic acid derivatives in high diastereo- and enantioselectivity by enantioselective hydrogenation in accordance with the following scheme
wherein
X, Ar, n, and m are defined hereinand corresponding salts thereof.
PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY ENRICHED CYCLIC BETA-ARYL OR HETEROARYL CARBOCYCLIC ACIDS
申请人:Bachmann Stephan
公开号:US20130253201A1
公开(公告)日:2013-09-26
The present invention relates to a process for the preparation of cis substituted cyclic β-aryl or heteroaryl carboxylic acid derivatives in high diastereo- and enantioselectivity by enantioselective hydrogenation in accordance with the following scheme
wherein
X, Ar, n, and m are defined herein and corresponding salts thereof.