K2S2O8-Mediated 1,2-Hydroxycarbonylation of Alkenes to Construct Hydroxyl-Functionalized Chroman-4-Ones

Difunctionalization of alkenes allows the rapid construction of complex molecules with high selectivity and efficiency in organic synthesis. Herein, we first describe a 1,2-hydroxycarbonylation of alkenes for the preparation of hydroxyl-functionalized chroman-4-ones through the cooperative action of inorganic oxidants and organic acids. The transformation is initiated by the formation of an acyl radical, and then experiences intramolecular 6-exo-trig radical cyclization and hydroxylation process. It is notable that the hydroxyl group in the final products originate from organic acids without the use of any transition-metal catalysts. To further demonstrate the practicality and mechanism of this method, the gram-scale reaction and a series of control experiments including gas chromatography-mass spectrometry (GC-MS) and infrared (IR) absorption spectroscopy experiments were performed, and the corresponding intermediates were successfully captured.