Rhodium(ii)-catalyzed C–H aminations using N-mesyloxycarbamates: reaction pathway and by-product formation

Abstract

DFT study to elucidate the mechanism of Rh-catalyzed C–H aminations with N-mesyloxycarbamates and the pathway by which by-products formed.

A Mechanistic Study of the Stereochemical Outcomes of Rhodium‐Catalysed Styrene Aziridinations

“…The formation of the metal nitrene from the Ph-TrocNHOMs, KOAc and Rh 2 (OAc) 4 in CH 2 Cl 2 was first calculated. As observed before, [17] the metal nitrenoid species (NRO 1 , with the OMs still bound to the nitrogen) is the resting state of the catalytic cycle, being more stable than the corresponding metal nitrene 1 (Figure 2). However, in contrast to the CÀ H amination reaction, the formation of the rhodium nitrene species is the rate determining step in the aziridination reaction.…”

“…Rhodium Nitrene Species from Rh 2 (OAc) 4 . As observed before, [17] the metal nitrenoid species (NRO 1 , with the OMs still bound to the nitrogen) is the resting state of the catalytic cycle, being more stable than the corresponding metal nitrene 1 ( Figure 2). As observed before, [17] the metal nitrenoid species (NRO 1 , with the OMs still bound to the nitrogen) is the resting state of the catalytic cycle, being more stable than the corresponding metal nitrene 1 ( Figure 2).…”

“…[17] Dispersion effects were treated with the D3 correction. The reaction and activation energies were calculated using KohnÀ Sham density functional theory (DFT) with the PerdewÀ BurkeÀ Ernzerhof (PBE) approximation for the exchange-correlation energy.…”

“…The PBE pure functional has been previously identified as a suitable method to afford reliable results with rhodium carboxylate dimers derived nitrene species. [17] Dispersion effects were treated with the D3 correction. [19] Singlepoint energy calculations were performed with the polarizable continuum model (PCM) [20] and the Solvation Model based on Density (SMD) [21] in CH 2 Cl 2 (ɛ = 8.93) on the gas-phase optimized geometries.…”

“…[10d] Recently, we have disclosed a DFT study on the mechanism of the rhodium-catalysed CÀ H amination with N-mesyloxycarbamates, which showed that the reaction proceeds via a concerted singlet pathway. [17] Herein, we report a detailed computational study of the mechanism of the aziridination with N-mesyloxycarbamates catalysed by rhodium carboxylate dimers. [18] This study highlights the importance of minimum energy crossing point (MECP) between the triplet and closed-shell singlet surfaces in aziridination reactions and provides highly valuable information to explain the stereoselectivity of the reaction.…”