Ruthenium(II)‐Catalyzed C−H Activation of Imidamides and Divergent Couplings with Diazo Compounds: Substrate‐Controlled Synthesis of Indoles and 3
<i>H</i>
‐Indoles
作者:Yunyun Li、Zisong Qi、He Wang、Xifa Yang、Xingwei Li
DOI:10.1002/anie.201606316
日期:2016.9.19
Indoles are an important structural motif that is commonly found in biologically active molecules. In this work, conditions for divergentcouplings between imidamides and acceptor–acceptor diazo compounds were developed that afforded NH indoles and 3H‐indoles under ruthenium catalysis. The coupling of α‐diazoketoesters afforded NH indoles by cleavage of the C(N2)−C(acyl) bond whereas α‐diazomalonates
arylnitrones and diazo compounds by C–H activation/[4 + 1] annulation with a C(N2)–C(acyl) bond cleavage is reported, and 2,3-disubstituted NH indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh(III)-catalyzed synthesis of homologous series, this method
Multisubstituted indoles were synthesized via a one-pot tandem copper-catalyzed Ullmann-type C–N bond formation/intramolecular cross-dehydrogenativecoupling process at 130 °C in DMSO. The methodology allows practical and modular assembly of indoles in good to excellent yields from readily available aryl iodides and enamines.
An Oxidant-Free Strategy for Indole Synthesis via Intramolecular C–C Bond Construction under Visible Light Irradiation: Cross-Coupling Hydrogen Evolution Reaction
We describe here an oxidant-free strategy to synthesize indoles, i.e., under visible-light irradiation (λ = 450 nm), catalytic amounts of an iridium(III) photosensitizer and cobaloxime catalyst transform various N-arylenamines exclusively into indoles. Our methodology affords indoles in good to excellent yields under mild reaction conditions and produces H2 as the only byproduct. Spectroscopic and
The construction of substituted indole skeletons is always an important concern of synthetic chemists because of its prevalent structure found in natural products and biological molecules. Here, we succeeded in preparing indoles and their derivativesfrom a wide variety of simple enamines viaradical cyclization only with catalytic amounts of an iridium(III) photosensitizer (PS) in DMSO solution under