Non-catalyzed addition of heterocyclic thiols and 5-substituted-1H-tetrazoles to vinyl ethers

The alkylation of 1-substituted 1H-tetrazole-5-thiols and 4-substituted 4 H-1,2,4-triazole-3-thiols with alkyl halides or sulfonates lead to the formation of S-alkylated products regardless of the substituent on the heterocycle. In this work, we found that substituted 1H-tetrazole-5-thiols and 4 H-1,2,4-triazole-3-thiols readily reacted with vinyl ethers in the absence of a catalyst to exclusively form N-substituted 1H-tetrazole-5(4H)-thiones and 1H-1,2,4-triazole-5(4H)-thiones, respectively. Furthermore, the reactions of 5-substituted-1H-tetrazoles with vinyl ethers under the same conditions selectively yielded 2,5-disubstitued tetrazoles.