C–H bond activation reactions by TpMe2Ir(iii) centres. Generation of Fischer-type carbenes and development of a catalytic system for H/D exchange†
Laura L. Santos,Kurt Mereiter,Margarita Paneque,Christian Slugovc,Ernesto Carmona
New Journal of Chemistry Pub Date : 11/28/2002 00:00:00 , DOI:10.1039/B209324C
Abstract

The unsaturated [TpMe2Ir(C6H5)2] fragment, readily generated from [TpMe2Ir(C6H5)2(N2)], or from [TpMe2Ir(C2H4)2] and C6H6, is able to induce the regioselective cleavage of two sp3 C–H bonds of anisole, with formation of a Fischer-type carbene, 1. The process involves additionally ortho-metallation of the anisole aromatic ring, hence three C–H bonds are sequentially broken, the last one in the course of an α-H elimination reaction. Phenetole (ethyl phenyl ether) gives an analogous product, 3, despite the possibility of competitive α- or β-H eliminations in the last step. For C6H5NMe2, two hydride-carbenes, 5a and 5b, are produced. In the latter, the aniline phenyl ring is also metallated, but the former contains a C6H5 aryl group and a C6H5N(Me)CH carbene ligand. The same Ir(III) fragment, viz. [TpMe2Ir(C6H5)2], alternatively generated from C6H6 and [TpMe2Ir(η4-CH2[double bond, length as m-dash]C(Me)C(Me)[double bond, length as m-dash]CH2)], accomplishes the efficient, catalytic H/D exchange between C6D6 (used as the deuterium source) and a variety of organic and organometallic molecules that contain C–H bonds of different nature.

Graphical abstract: C–H bond activation reactions by TpMe2Ir(iii) centres. Generation of Fischer-type carbenes and development of a catalytic system for H/D exchange