Abstract
Vilsmeier-Haack reactions of 1, 3(2H, 4H)-isoquinolinediones (1a, b) with dimethylformamide and POCl3 afforded 4-hydroxymethylene-1, 3(2H, 4H)-isoquinolinediones (2a, b) in good yields.Similar reactions of 1a, b using formanilides instead of N, N-dimethylformamide gave the 4-anilinomethylene compounds (3a, b). Chlorinations of 2a, b with POCl3 in CHCl3 or tetrahydro-furan gave the 4-chloromethylene compounds 4a, b. Treatment of 2a with POCl3 in the absence of solvent afforded 4a and 1, 3-dichloro-4-(dichloromethyl)isoquinoline (5). Compound 2b reacted with various amines including ketone reagents to form the corresponding 4-aminomethylene compounds 7a-e, and 7a-e as well as 3a, b could also be prepared from the reactions of 4b with appropriate amines. Catalytic hydrogenation of 2b resulted in the formation of 2, 4-dimethyl-1, 3(2H, 4H)-isoquinolinedione (8) and 2, 2', 4, 4'-tetramethyl[4, 4'-biisoquinoline]-1, 1', 3, 3'(2H, 2'H-4H, 4'H)-tetrone (9).
