N-heterocyclic carbene ligands in nickel-catalyzed Suzuki–Miyaura cross-coupling of aryl esters and carbamates is investigated. Imidazol-2-ylidene bearing 2-adamantyl groups at its nitrogen atoms generates the most active nickel species among the ligands examined, allowing cross-coupling of a range of aryl carbamates and pivalates. Unlike the previously reported systemusing tricyclohexylphosphine, this protocol
Photochemically Driven Nickel‐Catalyzed Carboxylative C−N Coupling: Scope and Mechanism**
作者:Seifallah Abid、Kevin P. Quirion、Yi Yang、Renhe Tang、Binh Khanh Mai、Peng Liu、Anis Tlili
DOI:10.1002/chem.202301271
日期:2023.8.4
The carboxylative Buchwald–Hartwigamination is disclosed herein under mild conditions of temperature and under atmospheric pressure of CO2. The key to success is the use of a dual strategy organophotocatalysis/nickel catalysis under visible light irradiation. The developed conditions demonstrated high functional group tolerance toward (hetero)aryl iodide and bromide. Furthermore, preliminary mechanistic
N,B-Bidentate Boryl Ligand-Supported Iridium Catalyst for Efficient Functional-Group-Directed C–H Borylation
作者:Guanghui Wang、Li Liu、Hong Wang、You-Song Ding、Jing Zhou、Shuai Mao、Pengfei Li
DOI:10.1021/jacs.6b11867
日期:2017.1.11
Convenient silylborane precursors for introducing N,B-bidentate boryl ligands onto transition metals were designed, prepared, and employed in ready formation of irdium(III) complexes via Si-B oxidative addition. A practical, efficient catalytic ortho-borylation reaction of arenes with a broad range of directing groups was developed using an in situ generated catalyst from the silylborane preligand 3c and [IrCl(COD)](2).
Directed Ortho Borylation of Phenol Derivatives Catalyzed by a Silica-Supported Iridium Complex
The directed ortho borylation of phenol derivatives protected with an N,N-diethylcarbamoyl group was efficiently catalyzed by an immobilized monophosphine-Ir system, which was prepared in situ from [Ir(OMe)(cod)](2) and a silica-supported, compact phosphine. The utility of the carbamoyloxy group as a leaving group for metal-catalyzed cross-coupling reactions was demonstrated by its utilization in the synthesis of a terphenyl derivative.
Nickel-catalyzed C−H arylation of benzoxazoles and oxazoles: Benchmarking the influence of electronic, steric and leaving group variations in phenolic electrophiles
作者:Deborah F. Steinberg、Morgan C. Turk、Dipannita Kalyani
DOI:10.1016/j.tet.2017.02.021
日期:2017.4
Electronic, steric and leaving group effects for Ni-catalyzed direct arylations using C-O electrophiles were benchmarked. The scope of arylations with pivalates was general with respect to both the electronics on the electrophile and the azoles. Furthermore, the arylation of azoles with tosylates, mesylates and carbamates with varying electronics was explored, and showed electronic trends similar to those of the pivalate reactions. Finally, the relative rate of arylation of 5-methyl benzoxazole with two electronically-similar electrophiles bearing different leaving groups was established. The results from these studies implicate the following order of relative reactivity: mesylates > pivalates > carbamates. (C) 2017 Elsevier Ltd. All rights reserved.