Michael Reactions of 4-Acylmethylene-1, 3 (2H, 4H)-isoquinolinediones with Malononitrile

Abstract

2-Methyl-1, 3 (2H, 4H)-isoquinolinedione (I) reacted with methylglyoxal to form 1, 1-bis (2-methyl-1, 3-dioxo-1, 2, 3, 4-tetrahydroisoquinolin-4-yl) acetone (IV) in 58% yield. The Michael reaction of 2-methyl-4-phenacylidene-1, 3 (2H, 4H)-isoquinolinedione (II) with malononitrile gave 1H-pyrano [2, 3-c] isoquinoline (VI) and furo [2', 3' : 2, 3] furo [5, 4-c] isoquinoline (VII) derivatives in a ratio of 2 : 3. In the reaction of IV with malononitrile, retrograde Michael reaction occurred and resulted in the formation of 1, 1H-pyrano [2, 3-c] isoquinoline (IX) and 4-3'-furyl-1, 3 (2H, 4H)-isoquinolinedione (X) derivatives. X-Ray structure analyses of VII and IX were performed.