Cobalt-Catalyzed Oxidant-Free Spirocycle Synthesis by Liberation of Hydrogen

Organic Letters, Journal Year: 2017, Volume and Issue: 19(17), P. 4640 - 4643

Published: Aug. 21, 2017

The first example of oxidant-free cobalt-catalyzed synthesis five-membered spirocycles is reported from benzimidates and maleimides utilizing nitrobenzene as promoter. In contrast to previously known oxidative C–H functionalization reactions, this transformation occurs efficiently in the absence oxidant accompanied by liberation hydrogen. spiro-lactams were readily achieved hydrolysis as-prepared spirocyclic compounds. Cp*Rh(III) catalyst shows poor reactivity.

Language: Английский

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Co(III)-Catalyzed Coupling-Cyclization of Aryl C–H Bonds with α-Diazoketones Involving Wolff Rearrangement

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(2), P. 1308 - 1312

Published: Jan. 16, 2018

An unusual cobalt(III)-catalyzed cross-coupling/cyclization of aryl C–H bonds N-nitrosoanilines with α-diazo-β-ketoesters has been achieved. This protocol features a unique combination Csp2-H activation/Wolff rearrangement process, allowing for the rapid assembly quaternary 2-oxindoles. The empirical evidence and density functional theory (DFT) calculations reveal trapping process transient acceptor ketene intermediates by cobalt metallocycles.

Language: Английский

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Cobalt(III)-Catalyzed C–C Coupling of Arenes with 7-Oxabenzonorbornadiene and 2-Vinyloxirane via C–H Activation

Organic Letters, Journal Year: 2016, Volume and Issue: 18(15), P. 3802 - 3805

Published: July 8, 2016

Co(III)-catalyzed mild C–C couplings of arenes with strained rings such as 7-oxabenzonorbornadienes and 2-vinyloxirane have been realized. The transformation is proposed to undergo ortho C–H activation, olefin insertion, subsequent β-oxygen elimination. A broad range synthetically useful functional groups are compatible, thus providing a new entry access diversely 2-functionalized indoles.

Language: Английский

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Mixed Directing‐Group Strategy: Oxidative C−H/C−H Bond Arylation of Unactivated Arenes by Cobalt Catalysis

Angewandte Chemie International Edition, Journal Year: 2016, Volume and Issue: 55(43), P. 13571 - 13575

Published: Sept. 21, 2016

A mixed directing-group strategy for inexpensive [Co(acac)3 ]-catalyzed oxidative C-H/C-H bond arylation of unactivated arenes has been disclosed. This enables the a wide range benzamide and arylpyridines effectively to afford novel bifunctionalized biaryls, which are difficult achieve by common synthetic routes. Two different pathways, namely, single-electron-transmetalation process (8-aminoquinoline-directed) concerted metalation-deprotonation (pyridine-directed), were involved activate two inert aromatic C-H bonds. Moreover, aryl radicals have trapped 2,6-di-tert-butyl-4-methylphenol form benzylated products. unique should be useful in design other arene cross-couplings as well.

Language: Английский

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Mild Cobalt(III)‐Catalyzed Allylative C−F/C−H Functionalizations at Room Temperature

Chemistry - A European Journal, Journal Year: 2017, Volume and Issue: 23(50), P. 12145 - 12148

Published: July 4, 2017

Sustainable, cobalt-catalyst enabled, synthetically significant C-F/C-H functionalizations were achieved with an ample substrate scope at ambient temperature of 25 °C, thereby delivering perfluoroallylated heteroarenes. Detailed experimental and computational mechanistic studies on the provided strong support for a facile C-F cleavage.

Language: Английский

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