A Bifunctional Copper Catalyst Enables Ester Reduction with H<sub>2</sub>: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
作者:Birte M. Zimmermann、Trung Tran Ngoc、Dimitrios-Ioannis Tzaras、Trinadh Kaicharla、Johannes F. Teichert
DOI:10.1021/jacs.1c09626
日期:2021.10.13
activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered “soft” copper(I) hydrides to previously
采用基于铜 (I)/NHC 配合物和胍有机催化剂的双功能催化剂,促进了以 H 2作为末端还原剂的催化酯还原成醇。这里采用的方法能够通过氢键同时活化酯,并从 H 2形成亲核的氢化铜 (I) ,从而导致氢化物催化转移到酯。由胍亚基介导的质子穿梭进一步促进了还原步骤。这种酯还原的双功能方法首次将通常认为的“软”氢化铜 (I) 的反应性转变为以前不反应的“硬”酯亲电子试剂,并为用催化剂和 H 2替代化学计量还原剂铺平了道路.
Iridium‐Catalyzed Direct CH Amidation with Weakly Coordinating Carbonyl Directing Groups under Mild Conditions
作者:Jinwoo Kim、Sukbok Chang
DOI:10.1002/anie.201310544
日期:2014.2.17
An iridium‐catalyzed direct CH amidation of weakly coordinating substrates, in particular of those bearing ester and ketone groups, under very mildconditions has been developed. The observed high reaction efficiency was achieved by the combined use of acetic acid and lithium carbonate as additives.
Regio- and Chemoselective CH Chlorination/Bromination of Electron-Deficient Arenes by Weak Coordination and Study of Relative Directing-Group Abilities
作者:Xiuyun Sun、Gang Shan、Yonghui Sun、Yu Rao
DOI:10.1002/anie.201300176
日期:2013.4.15
It's all relative: A practical and efficient PdII‐catalyzed regio‐ and chemoselectivechlorination/bromination has been developed for the facile synthesis of a broad range of aromatic chlorides. The reaction demonstrates excellent reactivity, good functional‐group tolerance, and high yields. A preliminary study was conducted to evaluate relative directing‐group abilities of various functionalities
Rhodium-Catalyzed Cascade Oxidative Annulation Leading to Substituted Naphtho[1,8-<i>bc</i>]pyrans by Sequential Cleavage of C(sp<sup>2</sup>)–H/C(sp<sup>3</sup>)–H and C(sp<sup>2</sup>)–H/O–H Bonds
作者:Xing Tan、Bingxian Liu、Xiangyu Li、Bin Li、Shansheng Xu、Haibin Song、Baiquan Wang
DOI:10.1021/ja3075242
日期:2012.10.3
efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp(2))-H/C(sp(3))-H and C(sp(2))-H/O-H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp(2))-H/C(sp(3))-H bonds and annulation with alkynes
Transformation of alkyl N-(vinyloxy)benzimidates to alkyloxazoles proceeds through the intermediates: a charge-separated 1,2-oxazetidine derivative and then 1-hydroxy-2-[[methylthio(phenyl)methylene]imino]maleic acid diester, while their photochemical transformation takes place via a concerted [1,3] sigmatropic shift. As the extension of this reaction, the preparation of the precursor proposed for