Understanding the Regioselectivity and the Molecular Mechanism of [3+2] Cycloaddition Reactions between Nitrous Oxide and Conjugated Nitroalkenes: A DFT Computational Study

Regiochemical aspects and the molecular mechanism of the [3 + 2] cycloaddition between nitrous oxide and conjugated nitroalkenes were evaluated on the basis of the wb97xd/6-311 + G(d) (PCM) computational study. It was found that, independently of the nature of the nitroalkene, all considered processes are realized via polar, single-step mechanisms. All attempts at the localization of hypothetical zwitterionic intermediates were unsuccessful. Additionally, the DFT computational study suggested that, in the course of the reaction, the formation of respective Delta(2)-4-nitro-4-R-1-5-R-2-1-oxa-2,3-diazolines was preferred from the kinetic point of view.

Automated summary

In this study, the regiochemical aspects and molecular mechanism of the [3 + 2] cycloaddition reaction between nitrous oxide and conjugated nitroalkenes were analyzed through computational calculations. It was discovered that the reaction proceeds via a polar, single-step mechanism regardless of the nature of the nitroalkene, and attempts to locate hypothetical zwitterionic intermediates were unsuccessful. The DFT computational study further revealed that the kinetic preference is the formation of corresponding Delta(2)-4-nitro-4-R-1-5-R-2-1-oxa-2,3-diazolines.