BIS-AZAHETEROCYCLES .4. THERMAL AND PHOTOCHEMICAL-REACTIONS OF SOME 3,3'-BISQUINAZOLINE-4,4'-DIONES

Pyrolysis of 3,3'-bis(1,2,3,4-tetrahydroquinazoline)-4,4'-dione (1) at 270-degrees gives 2-(2-chlorophenyl)- 1,2-dihydro-4(3H)-quinazolinone (4) and 2-(2-chlorophenyl)-4(3H)-quinazolinone (5). Similarly the pyr olysis of 2,2'-diaryl-1,1'-dimethyl-3,3'-bis(1, 2, 3, 4-tetrahydroquin azoline)4, 4'-dione (2a, Ar = phenyl, 2b, Ar = 4-methoxyphenyl) yields 2-aryl-1-methyl-1,2-dihydro-4-(3H)-quinazolinone (6a/6b) and 2-aryl-1 -methyl-4(3H)-quinazolinone (7a/7b) along with a dimeric compound 3, 3 '-diaryl-1, 1'-dimethyl-2, 2'-bis(1, 2, 3, 4-tetrahydroquinazoline)-4, 4'-dione (8a/8b). However, thermolysis of 3, 3'-bis(spiro[cyclohexane -1, 2'(1'H)-quinazolin]-4'(3'H)-one) (3) at 275-degrees affords 2,5-di (2-aminophenyl)-1,3,4-oxadiazole (9) and 1,2,3,4-tetrahydro-9(10H)acri dinone (10). Photolysis of 1, 2a, 2b and 3 furnishes the products 5, 7 a, 7b and piro[cyclohexane-1,2'(1'H)-quinazolin]-4'(3'H)-one (11) resp ectively.