Effective N-methylation of nitroarenes with methanol catalyzed by a functionalized NHC-based iridium catalyst: a green approach to N-methyl amines. Issue 10 (11th May 2020)

• Record Type: Journal Article
• Authors: González-Lainez, Miguel; Jiménez, M. Victoria; Passarelli, Vincenzo; Pérez-Torrente, Jesús J.
• Is Part Of: Catalysis science & technology. Volume 10:Issue 10(2020)
• Page Start: 3458
• Page End: 3467
• Publication Date: 2020-05-11
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d0cy00707b
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : An Ir–NHC compound catalyzes the borrowing-hydrogen reduction of nitroarenes into N -methyl amines with methanol through a direct mechanism. Abstract : Compound [IrBr(CO)2 (κC- t BuImCH2 PyCH2 OMe)] featuring a flexible pyridine/OMe functionalized NHC ligand κ 1 C coordinated efficiently catalyzes the selective N -monomethylation of nitroarenes using methanol as both the reducing agent and the C1 source. A range of functionalized nitroarenes including heterocyclic or sterically hindered derivatives have been efficiently converted to the corresponding N -monomethyl amines in good yields at low catalyst loadings using sub-stoichiometric amounts of Cs2 CO3 as a base. Mechanistic investigations support a borrowing-hydrogen mechanism in which methanol acts as the hydrogen source and methylating agent. Further, the hydrogen transfer reduction of nitrobenzene to aniline under optimized reaction conditions should proceed through a direct mechanism involving nitrosobenzene and N -phenylhydroxylamine intermediates.