Pt(IV)-catalyzed generation and [4+2]-cycloaddition reactions of o-quinone methides

Novel intermolecular and intramolecular generations of ortho-quinone methides and their formal [4+2]-cycloaddition reactions with olefins catalyzed by PtCl₄ and AuCl₃ under mild conditions have been developed. Good to excellent yields (up to 99%) and diastereoselectivity (up to >99:1) of the chromans were obtained. PtCl₄ was found to be effective and compatible with various functional groups present in the substrates. A mechanism accounting for its catalytic cycle is proposed and discussed.     

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.