Key mechanistic insights into the intramolecular C-H bond amination and double bond aziridination in sulfamate esters catalyzed by dirhodium tetracarboxylate complexes

Computational insights into Ir(iii)-catalyzed allylic C-H amination of terminal alkenes: mechanism, regioselectivity, and catalytic activity

Computational studies on Ir(iii)-catalyzed intermolecular branch-selective allylic C–H amination of terminal olefins with methyl dioxazolone have been carried out to investigate the mechanism, including the origins of regioselectivity and catalytic activity difference. The result suggests that the reaction proceeds through generation of active species, alkene coordination, allylic C–H activation, decarboxylation, migratory insertion, and protodemetalation. The presence of AgNTf₂ could thermodynamically promote the formation of catalytically active species [Cp*Ir(OAc)]⁺. Both the weaker Ir–C(internal) bond and the closer interatomic distance of N⋯C(internal) in the key allyl-Ir(v)-nitrenoid intermediate make the migratory insertion into Ir–C(internal) bond easier than into the Ir–C(terminal) bond, leading to branch-selective allylic C–H amidation. The high energy barrier for allylic C–H activation in the Co system could account for the observed sluggishness, which is mainly ascribed to the weaker coordination capacity of alkenes to the triplet Cp*Co(OAc)⁺ and the deficient metal⋯H interaction to assist hydrogen transfer.

DFT studies on Ir(iii)-catalyzed branch-selective allylic C–H amination of terminal olefins with methyl dioxazolone have been carried out to investigate the mechanism, including the origins of regioselectivity and catalytic activity difference.

Chemoselective Intramolecular Formal Insertion Reaction of Rh-Nitrenes into an Amide Bond Over C-H Insertion

The past few decades have witnessed extensive efforts to disclose the unique reactivity of metal-nitrenes, because they could be a powerful synthetic tool for introducing the amine functionality into unactivated chemical bonds. The reactivity of metal-nitrenes, however, is currently mainly confined to aziridination (an insertion into a C=C bond) and C-H amination (an insertion into a C-H bond). Nitrene insertion into an amide C-N bond, however, has not been reported so far. In this work we have developed a rhodium-catalyzed one-nitrogen insertion into amide C-N and sulfonamide S-N bonds. Experimental and theoretical analyses based on density functional theory indicate that the formal amide insertion proceeds via a rhodium-coordinated ammonium ylide formed between the nitrene and the amide nitrogen, followed by acyl group transfer concomitant with C-N bond cleavage. Mechanistic studies have allowed rationalization of the origin of the chemoselectivity observed between the C-H and amide insertion reactions. The methodology presented herein is the first example of an insertion of nitrene into amide bonds and provides facile access to unique diazacyclic systems with an N-N bond linkage.

Cobalt-catalysed unactivated C(sp3)–H amination: two-state reactivity and multi-reference electronic character

A remarkable two-state reactivity scenario and an unusual multi-reference character have been computationally found in Co-catalysed C(sp³)–H amination. In addition, the investigation on the additive, aminating reagent, metal center, and auxiliary ligand provides implications for development of new catalytic C–H functionalization systems.