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.
<i>C</i>-Alkylation of <i>N</i>-alkylamides with styrenes in air and scale-up using a microwave flow reactor
作者:Joshua P. Barham、Souma Tamaoki、Hiromichi Egami、Noriyuki Ohneda、Tadashi Okamoto、Hiromichi Odajima、Yoshitaka Hamashima
DOI:10.1039/c8ob02282h
日期:——
N-alkylamides with styrenes is reported, proceeding in ambient air/moisture to give arylbutanamides and pharmaceutically-relevant scaffolds in excellent mass balance. Various amide and styrenederivatives were tolerated, rapidly affording molecular complexity in a single step; thus highlighting the future utility of this transformation in the synthetic chemistry toolbox. Reaction scalability (up to
Electrochemical 1,4-reduction of α,β-unsaturated ketones with methanol and ammonium chloride as hydrogen sources
作者:Binbin Huang、Yanan Li、Chao Yang、Wujiong Xia
DOI:10.1039/c9cc02368b
日期:——
sustainable, chemoselective 1,4-reduction of α,β-unsaturatedketones by means of an electrochemical method is presented, wherein the extremely inexpensive ammonium chloride (NH4Cl) is applied as the only additive. The reaction proceeds smoothly in the air at ambient temperature. Mechanistic studies reveal that both NH4Cl and solvent methanol work as hydrogen donors.
Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetrichydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones.
Chelate ring size effects of Ir(P,N,N) complexes: Chemoselectivity switch in the asymmetric hydrogenation of α,β-unsaturated ketones
作者:Zsófia Császár、Eszter Z. Szabó、Attila C. Bényei、József Bakos、Gergely Farkas
DOI:10.1016/j.catcom.2020.106128
日期:2020.11
led to the conclusion that the activity, chemo- and enantioselectivity in the hydrogenation of α,β-unsaturatedketones are highly dependent on the combination of the two bridge lengths. It has been found that a minor change in the ligand's structure, i. e. varying the value of m from 1 to 0, can switch the chemoselectivity of the reaction, from 80% CO to 97% CC selectivity.