Facile routes to 1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazines and 1,2,4‐triazino[3,4‐b][1,3,4]thiadiazine by heteropolyacides

Abstract

Abstractmagnified imageCyclization of 4‐amino‐6‐methyl‐3‐propargylmercapto‐1,2,4‐triazine‐5‐one 3 and 4‐amino‐3‐propargyl mercapto‐1,2,4‐triazole derivatives 6 were afforded 1,2,4‐triazino[3,4‐b][1,3,4]thiadiazines 4 and 1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazines 7 in presence of heteropolyacids, H14[NaP5W29MoO110] and H6P2W18O60 in high yields. Among used heteropoly acids, the yields were higher with H14‐P5Mo, caused to their high acid strengths.