Iridium-Catalyzed Dehydrogenative Reactions

N-Methylation of Amines with Methanol Catalyzed by Iridium(I) Complexes Bearing an N,O-Functionalized NHC Ligand

“…On the other hand, the N -alkylation of aliphatic amines selectively affords N , N -dimethylated amines which is in agreement with previous results. − Thus, benzylamine was selectively transformed in N , N -dimethyl-1-phenylmethanamine ( 7k ) in 15 h. However, N -methylation of cyclohexylamine required a higher catalyst loading and longer reaction time to achieve complete conversion to the N , N -dimethylcyclohexanamine product ( 7l ). In this case, it was possible to observe the formation of the monomethylated intermediate product, N -methylcyclohexanamine ( 6l ), which is the major product at very low conversions, and its transformation to 7l at higher conversions.…”

“…The main challenge of this methodology is to overcome the high energy demand of methanol dehydrogenation ( i.e ., for methanol Δ H = 84 kJ·mol –1 vs 68 kJ·mol –1 for ethanol) . A number of homogeneous and heterogeneous transition-metal-based catalysts have been developed, with ruthenium , and iridium ,, catalysts being the most active. In addition, some examples of catalysts based on non-noble metalscobalt, iron, , or manganese , among others, have also been reported recently.…”

Nitrile Oxidation at a Ruthenium Complex leading to Intermolecular Imido Group Transfer

“…UV-visible absorption spectroscopy of the completed reaction revealed an MLCT band at 415 nm, which was consistent with an earlier report of a sulfurcoordinated [Ru(terpy)(bipy)DMSO] 2+ adduct with an MLCT band at 412 nm (the MLCT band of the acetonitrile adduct, 1, was found to be 454 nm in the same report). 20 The DMSO-d 6 adduct, [Ru(terpy)(bipy)DMSO-d 6 ][NO 3 ] 2 (3), was synthesized in-situ by refluxing [Ru(terpy)(bipy)Cl]Cl with two equivalents of silver nitrate in DMSO-d 6 (Scheme 2). Chloride abstraction, followed by coordination of the DMSO-d 6 solvent, yielded an authentic sample of 3.…”

“…hydrogen peroxide, pyridine-N-oxide, or iodosobenzene. Although new cyclic classes of imido precursors like dioxazolones and isoxazolones have been developed in recent years to complement traditional azide and iminoiodinane precursors, 3 utilizing acetonitrile as both a reaction solvent and an imido precursor would be advantageous, both for the sake of cost and for the sake of simplicity.…”

Iridium-Catalyzed C-Alkylation of Methyl Group on N-Heteroaromatic Compounds using Alcohols

“…The hydrogen-borrowing process is an alternative method in which an alcohol is used as the alkylating reagent in a catalytic reaction. − This method is very environmentally friendly because the reaction generates only water, which is harmless, as a byproduct.…”