Metal-Free Oxidation of the Exocyclic C=C Bond in Para-QuinoneMethides to Aromatic Aldehydes Using PIDA

Introduction: Many approaches have been reported for the oxidative cleavage of alkenes into aldehydes; however, our method is mild, efficient, and offers high regioselectivity along with excellent functional group tolerance. Method: A metal-free strategy was employed for the selective oxidation of p-QMs, affording a variety of aromatic aldehydes. Results: In this method, metal-free oxidation of the exocyclic C=C bond of p-quinone methides to aromatic aldehydes was achieved using PIDA as the oxidant. Discussion: The resulting products were characterized using ¹H NMR, ¹³C NMR, and HRMS. Control experiments were conducted to investigate the reaction mechanism, and HRMS analysis of intermediates was performed to support the proposed pathway. Conclusion: The present work offers an alternative method for the oxidative cleavage of alkenes into aldehydes.