Addition of sulfonylphthalides to para-quinone methides: Selective 1,6-additions and oxidative annulations

Abstract

KO^tBu mediated addition of sulfonylphthalides to p-quinone methides led to the selective synthesis of isochroman-1,4-diones and addition products. Interestingly, isochroman-1,4-diones were obtained via an unprecedented oxidative annulation pathway. The present work highlights a wide variety of substrates, good yields, shorter reaction time and ambient reaction conditions. Furthermore, a few addition products were transformed into functionalized heterocyclic molecules. Additionally, the scale-up experiment suggests the practical feasibility of preparing isochroman-1,4-diones in higher-scale reactions.