Visible light catalyzed reaction of alpha-bromo-chalcones with chalcones: direct access to the urundeuvine scaffold

The alpha-keto vinyl radicals generated from alpha-bromochalcones under visible light photoredox catalyzed conditions were trapped by chalcones. The subsequent intramolecular cyclization of the resulting benzylic radicals led to the synthesis of dihydronaphthalenes, which were conveniently oxidized to the corresponding naphthalenes. The strategy was adopted successfully for synthesizing derivatives of urundeuvine chalcones, which are otherwise accessible only from natural sources.