Highly active iridium(i) complexes for catalytic hydrogen isotope exchange

Abstract

Practically convenient methods have been developed for the preparation of new iridium complexes, possessing bulky N-heterocyclic carbene and phosphine ligands; these routinely handled complexes are highly active catalysts within directed hydrogen isotope exchange processes.

Iridium-Catalysed ortho-Directed Deuterium Labelling of Aromatic Esters—An Experimental and Theoretical Study on Directing Group Chemoselectivity

“…Thin layer chromatography was carried out using Camlab silica plates coated with fluorescent indicator UV254 (Sigma-Aldrich), and were visualized using a Mineralight UVGL-25 lamp (Fisher Scientific UK Ltd., Loughborough, UK) or developed using vanillin solution. Catalysts 1a [20], 1b [16], and 1d [18] were prepared according to literature procedures. Esters 6c [32], 10a [33], 10b [34], 10c [35], 10d [36], 10e [37], and 13 [38] were prepared according to the corresponding literature procedures.…”

“…Over recent years, research in our laboratory has focused on the development of iridium(I) N-heterocyclic carbene (NHC)-ligated precatalysts of the type 1, and their application in HIE via ortho-directed C-H activation protocols (2→4 via 3, Scheme 1) [6,[16][17][18][19][20][21][22]. Despite the growing list of compatible directing groups, we [23] and others [24][25][26][27] have found these developed C-H activation methods less applicable in the labelling of aromatic esters under ambient conditions.…”

Chelation-assisted rhodium hydride-catalyzed regioselective H/D exchange in arenes

“…c o m / l o c a t e / t e t l e t are usually more active toward CÀH activation. [8][9][10][11] Thus, we synthesized rhodium hydride complexes A-F (Fig. 2).…”

“…12 Kerr reported efficient deuteration of 2-phenylpyridine using iridium carbene catalysts and deuterium gas. 10 The phenyl group of entries 2 and 8 received nearly quantitative deuteration at the ortho positions only after a long reaction time, and this is because two C-H bonds need to be activated. The pyrimidine unit of 5-(pyridine-2-yl)pyrimidine (entry 7) is more acidic at the 2-position, such that three positions were deuterated, which prolonged the reaction time.…”

Z-Selective Dimerization of Aromatic Terminal Alkynes Catalyzed by an Iridium(I)-N-Heterocyclic Carbene-Phosphine System

“…14 Such complexes are readily handled, and we have previously showcased the ability of these complexes to facilitate hydrogen isotope exchange by arene C-H activation, 14 with activity far in excess of the current industry standard, Crabtree's catalyst. 15 More recently, work within our laboratories has highlighted the extremely efficient performance of these novel complexes in selective hydrogenation reactions.…”