Convenient access to novel functionalized pyrazino[1,2-b]isoquinolin-6-one and diazepino[1,2-b]isoquinolin-7-one scaffolds via the Cushman multicomponent reaction followed by post-condensation

Post-multicomponent reaction modifications of Cushman reaction-derived 1,2,3,4-tetrahydroisoquinolin-4-carboxylic acids turned out to be a surprisingly underdeveloped strategy in scaffold-oriented synthesis. In this Letter, we describe a concise synthesis of hitherto unreported pyrazino- and diazepino-fused isoquinolones in two chemical operations. The synthesis involves the use, for the first time, of aryl glyoxals as carbonyl components for the Cushman multicomponent reaction.