A comparative study of Rh2-catalyzed intermolecular nitrene transfer reactions: mechanism and chemoselectivity

作者：Wang, Juping^*; Zheng, Kangcheng; Xiao, Rongxing; Qian, Li; Lin, Zijie

来源：Catalysis Science & Technology, 2022, 12(11): 3498-3505.

DOI：10.1039/d2cy00155a

• C-H AMINATION
• EFFECTIVE CORE POTENTIALS
• MOLECULAR CALCULATIONS
• SITE-SELECTIVITY
• BASIS-SETS
• CATALYST
• INSIGHT
• PSEUDOPOTENTIALS
• AMIDATION
• DESIGN

The mechanism and chemoselectivity of Rh-2-catalyzed intermolecular nitrene transfer reactions of carvone have been investigated using the M06L method. By comparing Rh-2(esp)(2)vs. Rh-2(OAc)(4) catalysis, the origin of aziridination-to-amination chemoselectivity is revealed. The stepwise radical pathways are preferred for aziridination and amination by the two Rh-2 catalysts. However, the Rh-2(esp)(2) and Rh-2(OAc)(4) catalysts have a large difference in their aziridination-to-amination chemoselectivity, and this difference stems from the steric effect. Exclusive aziridines are obtained by Rh-2(OAc)(4) because the pi-bond is more electron-rich and has a lower bond dissociation energy (BDE) compared to that of the sigma(C-H) bond. However, for Rh-2(esp)(2) catalysis, the disadvantage from the larger steric congestion compensates for the advantage from the lower BDE of the pi-bond in aziridination, leading to a similar yield of aziridine and amine. The stepwise mechanisms and ligand-dependent chemoselectivities of the intermolecular nitrene transfer reactions are strikingly different from those of the intramolecular ones. This work offers valuable information for the further development of highly efficient and selective catalysts, which can be applied to intermolecular nitrene transfer reactions.

• 单位
  广东药学院; 中山大学