Theoretical insights into the synthesis reaction mechanism of 1,2,3-triazole based on sakai reaction

• Published in: Tetrahedron 2021-01, Vol.77, p.131737, Article 131737
• Main Authors: Shang, Fangjian, Liu, Jianyong, Zhou, Panwang, Zhang, Chaoyang
• Format: Article
• Language: English
• Subjects: Density functional theory; Reaction mechanism; Sakai reaction
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2020.131737

Sakai reaction is an important method to synthetize 1,2,3-triazole by the addition of α, α-dichlorotosylhydrazones and amines. However, the difficulty of introducing the 1,2,3-triazole ring is often affected by the type of amine reagent. More calculation results and detailed mechanisms are used to screen which amine is more suitable for the Sakai reaction. In this study, the DFT calculations were carried out to study the reaction mechanism of Sakai reaction. Depending on the type of amines, two different paths for Sakai reaction were revealed by our calculations. For the triazolamine, an H atom must transfer from the amines to the diazine synchronously when the new C–N bond is formed. The transformation from trans- to cis- is necessary for the intermediate vinyldiazine. For aniline, the amine molecule can combine with trans-vinyldiazine directly without an H transfer due to the formation of a structure that is similar to NH4+ ion. [Display omitted] •The mechanism of Sakai reaction was studied in detail by using DFT method.•The reaction path is affected by the cis-trans isomerism of the intermediate vinyldiazine.•The yield is affected by the reaction path of the corresponding reactants.