Ryuzo Mizuguchi

Ring closure reactions of adducts of methacryloyl isocyanate to arylhydrazines and their related compounds

Methacryloyl isocyanate (MAI) reacted with arylhydrazines (1) to give semicarbazides (2) in good yields. Treatment of (2) with aqueous potassium hydroxide gave the corresponding 1-aryl-3-hydroxy- 1,2,4-triazoles (3), whereas thermal ring closure of (2) afforded isomeric 2,3-dihydro-2-aryl-1,2,4-triazole-3(1H)-ones (4). MAI reacted with benzamidine to give directly 1,3,5-triazine-2(1H)-one (10) by the loss of water. On the other hand, the reaction of MAI with 1,3-diphenyl- guanidine afforded the 1:1 adduct (11), which on thermal decomposition gave the perhydropyrimidin-6(1H)-one (12) and perhydro-1,3,5-triazine- 2,6-dione (13). The pathways for the formation of (4), (12) and (13) are also described