Transalkylation and Migration of N-Substituent upon Alkylation of 1,2,3-Triazoles Containing Good Leaving N-Substituents

• Published in: European journal of organic chemistry 2016-12, Vol.2016 (35), p.5897-5906
• Main Authors: Telegina, Lyudmila N., Kelbysheva, Elena S., Strelkova, Tatyana V., Ezernitskaya, Mariam G., Borisov, Yurii A., Smol'yakov, Aleksander F., Peregudov, Aleksander S., Rodionov, Alexey N., Ikonnikov, Nikolay S., Loim, Nikolay M.
• Format: Article
• Language: English
• Subjects: Alkylation; Density functional calculations; Metallocenes; Nitrogen heterocycles; Rearrangment
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201601146

The synthesis of four new 1,2,3‐triazole derivatives and seven 1,2,3‐triazolium salts that contain an organometallic group (i.e., cymantrenyl and ferrocenyl) at either the N‐1, N‐2, or N‐3 position was realized. The alkylation of organometallic and organic triazole derivatives was investigated, and as a result of these studies, it was found that the presence of a good leaving group at the heterocyclic nitrogen atom led to transalkylation and subsequent migration of the N‐1 substituent to the N‐2 position of the triazole moiety. The nucleophilicity of the counterion of the triazolium salt influenced the transalkylation and isomerization processes, which suggests that the elimination of the N‐substituent most likely occurs though a concerted mechanism with nucleophilic assistance from the counterion. Thus, a new approach to the synthesis of 2,4‐disubstituted 1,2,3‐triazoles has been developed. In the course of the synthesis of 1,2,3‐triazolium salts, the transalkylation and migration of the N‐1 substituent to the N‐2 position of the triazole moiety occurs if a good leaving group is present at the heterocyclic nitrogen atom. Cym = cymantrenyl; Fc = ferrocenyl.