Control over Organometallic Intermediate Enables Cp*Co(III) Catalyzed Switchable Cyclization to Quinolines and Indoles

ACS Catalysis, Journal Year: 2016, Volume and Issue: 6(4), P. 2352 - 2356

Published: March 1, 2016

Achieving controllable C–H functionalization to elaborate valuable compounds from simple chemicals is attractive and highly desirable, especially if nonprecious transition metal catalysts can be used. However, controlling selectivity in these transformations remains a continuous challenge synthetic chemists. Herein, we show for the first time that control over reactive organometallic intermediate enables switchable synthesis of quinoline indole amides alkynes through activation using Cp*Co(III). The keys this strategy are (1) introducing Lewis acid greatly accelerate dehydrative cyclization, which outcompete dehydrogenative (2) tuning directing group facilitate cyclization inhibit cyclization.

Language: Английский

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Cobalt‐Catalyzed Annulation Reactions via C−H Bond Activation

ChemCatChem, Journal Year: 2017, Volume and Issue: 10(4), P. 683 - 705

Published: Nov. 1, 2017

Abstract Considerable research attention has been directed towards the use of first‐row transition metals in organic synthesis. The more abundant, and less expensive cobalt is considered to be an effective alternative for second third‐row noble metals, especially C−H bond functionalization reactions. In this Minireview, we will summarize features, recent achievements Co‐catalyzed directing group assisted activation/cyclization reactions their mechanistic insights.

Language: Английский

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A Comparative Investigation: Group 9 Cp*M(III)-Catalyzed Formal [4 + 2] Cycloaddition as an Atom-Economic Approach to Quinazolines

Organic Letters, Journal Year: 2016, Volume and Issue: 18(9), P. 2090 - 2093

Published: April 25, 2016

A comparative study on the catalytic activity of different group 9 [Cp*M(III)] complexes in formal [4 + 2] cycloaddition arenes with rarely explored free imines and dioxazolones for construction multisubstituted quinazolines is reported herein. This investigation revealed that cobalt catalyst uniquely suited to this transformation due its strong Lewis acidity high sensitivity steric hindrance.

Language: Английский

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Cp*Co^III‐Catalyzed C(sp³)−H Bond Amidation of 8‐Methylquinoline

Chemistry - A European Journal, Journal Year: 2016, Volume and Issue: 22(27), P. 9135 - 9138

Published: May 11, 2016

An efficient and external oxidant-free, Cp*Co(III) -catalyzed C(sp(3) )-H bond amidation of 8-methylquinoline, using oxazolone as an amidating agent, is reported for the first time under mild conditions. The reaction selective tolerates a variety functional groups. Based on previous reports experimental results, deprotonation pathway proceeds through base-assisted concerted metalation process.

Language: Английский

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Cobalt(III)-Catalyzed Regio- and Stereoselective α-Fluoroalkenylation of Arenes with gem-Difluorostyrenes

Organic Letters, Journal Year: 2016, Volume and Issue: 18(24), P. 6320 - 6323

Published: Dec. 5, 2016

A cobalt(III)-catalyzed α-fluoroalkenylation of different arenes with readily available gem-difluorostyrenes has been realized under mild and redox-neutral conditions. This reaction occurs via a C–H activation pathway offers step-economical access to various 1,2-diaryl-substituted monofluoroalkenes in excellent Z selectivity moderate yields.

Language: Английский

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Indole Synthesis via Cobalt(III)-Catalyzed Oxidative Coupling of N-Arylureas and Internal Alkynes

Organic Letters, Journal Year: 2016, Volume and Issue: 18(8), P. 1776 - 1779

Published: March 29, 2016

A mild Co(III)-catalyzed oxidative annulation of N-arylureas and internal alkynes has been developed. The use less electrophilic ureas other than acetamides as directing groups is crucial for the reaction. broad range synthetically useful functional are compatible with this reaction, thus providing a new opportunity synthesis diverse indoles.

Language: Английский

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Recent advances using [Cp*Co(CO)I₂] catalysts as a powerful tool for C–H functionalisation

Dalton Transactions, Journal Year: 2017, Volume and Issue: 46(30), P. 9721 - 9739

Published: Jan. 1, 2017

This perspective highlights recent applications of Cp*Co^III catalysts in C–H functionalisation protocols, exemplifying both terminal couplings and heterocycle formation.

Language: Английский

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Cp*Co^III-Catalyzed Dehydrative C–H Allylation of 6-Arylpurines and Aromatic Amides Using Allyl Alcohols in Fluorinated Alcohols

Organic Letters, Journal Year: 2016, Volume and Issue: 18(9), P. 2216 - 2219

Published: April 27, 2016

Cp*CoIII-catalyzed C–H allylation of various aromatic bonds using allyl alcohols as allylating reagents is described. Improved reaction conditions fluorinated alcohol solvents afforded efficient directed 6-arylpurines, benzamides, and a synthetically useful Weinreb amide with good functional group compatibility.

Language: Английский

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Cooperative Co(III)/Cu(II)-Catalyzed C–N/N–N Coupling of Imidates with Anthranils: Access to 1H-Indazoles via C–H Activation

Organic Letters, Journal Year: 2016, Volume and Issue: 18(15), P. 3662 - 3665

Published: July 14, 2016

Cooperative cobalt- and copper-catalyzed C–H activation of imidate esters oxidative coupling with anthranils allowed efficient synthesis 1H-indazoles in the absence metal oxidants. The anthranil acts as a convenient aminating reagent well an organic oxidant this transformation. copper catalyst likely functions at stage N–N formation.

Language: Английский

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Catalyst‐Controlled Regiodivergent Alkyne Insertion in the Context of C−H Activation and Diels–Alder Reactions: Synthesis of Fused and Bridged Cycles

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(28), P. 8163 - 8167

Published: May 17, 2017

Abstract Rhodium(III)‐ and cobalt(III)‐catalyzed C−H activation of indoles coupling with 1,6‐enynes is discussed. Under rhodium(III) catalysis, the alkyne insertion follows 2,1‐regioselectivity a subsequent type‐I intramolecular Diels–Alder reaction (IMDA) to afford [6,5]‐fused cycles. When catalyzed by cobalt(III) congener, 1,2‐insertion preferred, followed rare type‐II IMDA, thus leading bridged [3,3,1]‐cycles. This selectivity was mainly tuned steric sensitivity catalyst.

Language: Английский

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