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 potassi um 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 gi ve 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-diphenylguanidine afforded t he 1:1 adduct (11), which on thermal decomposition gave the perhydropy rimidin-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.