Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
作者:Jiajun Wu、Christophe Darcel
DOI:10.1021/acs.joc.0c02505
日期:2021.1.1
A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogentransfer methodology. This protocol led specifically to imines in 30–91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64–72% yields when the
α‐Alkoxycarbonyl and α‐aminocarbonyl compounds are good substrates for the recently developed tosylhydrazide‐promoted Pd‐catalyzed cross‐coupling of carbonyls with aryl halides. The reaction gives rise to enolethers and enamines, respectively, which are useful synthetic intermediates in heterocyclic synthesis. Otherwise, they can be hydrolyzed to give α,α‐disubstituted aldehydes.
General and selective reductive amination of carbonyl compounds using a core–shell structured Co<sub>3</sub>O<sub>4</sub>/NGr@C catalyst
作者:Tobias Stemmler、Felix A. Westerhaus、Annette-Enrica Surkus、Marga-Martina Pohl、Kathrin Junge、Matthias Beller
DOI:10.1039/c4gc00536h
日期:——
The application of heterogenized non-noble metal-based catalysts in selective catalytic hydrogenation processes is still challenging. In this respect, the preparation of a well-defined cobalt-based catalyst was investigated by immobilization of the corresponding cobalt(II)-phenanthroline-chelate on Vulcan XC72R carbon powder. The formed coreâshell structured cobalt/cobalt oxide nanocomposites are encapsulated by nitrogen-enriched graphene layers. This promising cheap heterogeneous catalyst allows for an efficient domino reductive amination of carbonyl compounds with nitroarenes.
Unified Protocol for Fe-Based Catalyzed Biaryl Cross-Couplings between Various Aryl Electrophiles and Aryl Grignard Reagents
作者:Lei Wang、Yi-Ming Wei、Yan Zhao、Xin-Fang Duan
DOI:10.1021/acs.joc.9b00151
日期:2019.5.3
Ti(OEt)4/PhOM enabled a highly general iron-based catalyst system, which could efficiently catalyze the biaryl coupling reaction between various electrophiles (I, Br, Cl, OTs, OCONMe2, OSO2NMe2) and common or functionalized aryl Grignardreagents with high functional group tolerance. Selective couplings of aryl iodides and bromides over the corresponding oxygen-based electrophiles have been achieved, and
The α-arylation of sterically hindered silyl ketene acetals (SKAs) with sterically hindered aryl bromides occurs efficiently using Pd[P(t-Bu)3]2 as the optimal catalyst and ZnF2 as a promoter. Less sensitive P(t-Bu)3-based catalysts could be also employed but showed a lower activity. The reaction showed a broad scope with regard to both coupling partners, including heteroaryl bromides and cyclic SKAs