Alkylation of 1,3-diaryl-v-triazolo[1,5-a]benzimidazole (1) by trimethyloxonium salt afforded selectively the 4-methyl quaternary salt 2, whereas reaction with dimethyl sulfate at elevated temperature resulted in ring transformation, implying ring opening to a nitrenium cation and a subsequent electrophilic ring closure to give a benzimidazolylindazole product 5. Independent of the methylation, a similar easy thermal rearrangement was observed with alkylated 1,3-diaryl-v-triazolo[1,5-α]benzimidazolium (2 → 4) and the related benzothiazolium salt (7 → 8). Extension of the reaction to diaryl-v-triazolopyridinium salt (9 → 10 + 11) allowed observation of an additional novel reaction path that provided further support for the supposed reaction mechanism.
|Number of pages||3|
|Journal||Journal of Organic Chemistry|
|Publication status||Published - Dec 1 1997|
ASJC Scopus subject areas
- Organic Chemistry