1,2,3-Benzotriazin-4(3H)-ones and related systems. Part 5. Thermolysis of 3-aryl- and 3-alkenyl-1,2,3-benzotriazin-4(3H)-ones

Abstract

3-Aryl-1,2,3-benzotriazin-4(3H)-ones in boiling 1-methylnaphthalene or as solids undergo thermal decomposition and rearrangement to 9-acridones, whereas in paraffin oil at 300 °C only benzanilides are formed. In contrast, thermolysis of 3-(α-naphthyl)-1, 2, 3-benzotriazin-4(3H)-one and the isomeric 3-phenylnaphtho[2,3-d]-v-triazin4(3H)-one in hot paraffin oil yield benzo[c]acridone and benzo[c]phenanthridone, and benzo[b]acridone, respectively. Photolysis of the 3-arylbenzotriazinones in tetrahydrofuran also gives 9-acridones but in poor yields.

Some 3-alkenyl-1, 2, 3-benzotriazin-4(3H)-ones have been prepared. The 3-(prop-1-enyl) and 3-(β-styryl) derivatives undergo thermal decomposition to give 3-methyl- and 3-phenyl-quinolin-4(1H)-one, respectively, the latter in practicable yield.