Preparative resolution of bromocyclopropylcarboxylic acids
摘要:
A general and efficient method for the preparative resolution of alpha- and beta-bromocyclopropylcarboxylic acids has been developed. This protocol involves a sequence of two crystallizations with pseudo-enantiomeric amines, cinchonine, and cinchonidine, which yield both enantiomers of the acid in highly enriched form. Both alkaloids can be easily recovered and reused multiple times without any loss of efficacy. (C) 2014 Elsevier Ltd. All rights reserved.
A mild rhodium catalytic system has been developed to synthesize vinylcyclopropa[b]indolines through cyclopropanation of indoles with vinyl carbenoids generated from ringopening of cyclopropenes in situ. By employing a Rh-migration strategy, the products can be obtained with good to excellent E:Z ratios (≤99:1) and complete diastereoselectivity (≤99:1). This method is easy, has a low catalyst loading
已开发出一种温和的铑催化体系,通过将吲哚与原位环丙烯开环生成的乙烯基类胡萝卜素进行环丙烷化,来合成乙烯基环丙烷[ b ]二氢吲哚。通过采用Rh迁移策略,可以获得具有良好或优异的E:Z比(≤99:1)和完全非对映选择性(≤99:1)的产物。该方法容易,催化剂负载低并且适用于广泛的功能。
Asymmetric Nitrone Synthesis via Ligand-Enabled Copper-Catalyzed Cope-Type Hydroamination of Cyclopropene with Oxime
We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetriccyclopropene “hydronitronylation” process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic
Construction of All‐Carbon Chiral Quaternary Centers through Cu
<sup>I</sup>
‐Catalyzed Enantioselective Reductive Hydroxymethylation of 1,1‐Disubstituted Allenes with CO
<sub>2</sub>
construction of all-carbon chiral quaternary centers through reductive hydroxymethylation of 1,1-disubstituted allenes with CO2 has been developed. In the presence of a copper/Mandyphos catalyst, CO2 is transformed into an alcohol oxidation level by an asymmetric reductive C-C bond formation with allenes by using hydrosilane (HSi(OMe)2 Me) as a reductant. The resulting chiral homoallylic alcohols are
An asymmetric hydrophosphination of 3,3-disubstituted cyclopropenes catalyzed by Cu(I)-(R,R)-QUINOXP* is developed, affording a series of phosphine derivatives in high to excellent diastereo- and enantioselectivities.
开发了 Cu(I)-( R , R )-QUINOXP*催化的 3,3-二取代环丙烯的不对称氢膦化反应,提供了一系列具有高至优异的非对映选择性和对映选择性的膦衍生物。
Copper-Catalyzed Hydroamination: Enantioselective Addition of Pyrazoles to Cyclopropenes
作者:Minghao Wang、Julie C. Simon、Mengfei Xu、Stephanie A. Corio、Jennifer S. Hirschi、Vy M. Dong
DOI:10.1021/jacs.3c02971
日期:2023.7.12
Chiral N-cyclopropyl pyrazoles and structurally related heterocycles are prepared using an earth-abundant copper catalyst under mild reaction conditions with high regio-, diastereo-, and enantiocontrol. The observed N2:N1 regioselectivity favors the more hindered nitrogen of the pyrazole. Experimental and DFT studies support a unique mechanism that features a five-centered aminocupration.