Theoretical study on reaction mechanism of an N-heterocyclic carbene boryl azide with electron-deficient alkynes and nitriles

Abstract

A theoretical investigation of the [3?2] cycloaddition reaction of the NHC-boryl azide with alkynes and nitriles has been presented by using the DFT (B3LYP) method. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum model (PCM) for the solvent (C 6 H 6 ). The title reaction could produce two different five-membered products (1,4-regioisomer and 1,5-regioisomer). The reaction pathway involves a one-step mechanism through a [3?2] addition where two nitrogen atoms of the N-heterocyclic carbene boryl azide adds to the C:A (A=C or N) bond to form two new C-N or N-N bonds. For alkynes, the reactions can take place more easily to give 1,4-regioisomer product, while the reactions proceed for nitriles along the 1,5-regioisomer pathway. The reaction systems have high chemical reactivity with low barriers and could be favored. The calculations indicated that the cycloaddition reaction of alkynes and nitriles has the better regioselectivity. Our computational results are good consistent with the experimental observations of Merling and co-workers for [3?2]-dipolar cycloaddition reaction of N-heterocyclic carbene boryl azide.

The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect

“…PCM is widely used in studies of the solvation effect as the classical quantum chemical calculation method [27]. Many studies show that the results of PCM can be directly compared with the outcome of the experimental measurements,and the results are in good agreement with the experimental values [28–30]. To eliminate systematic error between the theoretical and experimental values, the calculations were multiplied by a calibration factor of 0.960 [31].…”

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

“…2]-dipolarcycloaddition reactions of 1,3-bis-phenyl-imidazol-2-ylidene dihydridoboron azide with CH 3 C:CCOCH 3 , PhC:CCOOCH 3 , HC:CC 6 H 4 -4-Cl and PhSO 2 C:N, CHCl 2 C:N, F 3 CC:N was studied by Zhang et al [142], who used DFT. The results suggested that two different five-membered products (a 1,4-regioisomer and a 1,5-regioisomer) could be formed.…”