Dicarbofunctionalization of Alkenes/Alkynes via CAN-Mediated Cyclization Reactions

Ceric ammonium nitrate (CAN) was utilized to transform readily available terminal alkenes/alkynes to the corresponding chroman-4-one/chromenoquinoline analogues. Interestingly, the type of unsaturation on the substrate dictates the course of the CAN-mediated cyclization reaction. With alkenes, sequential carbofunctionalization/cyclization cascade facilitated the formation of chroman-4-one, whilst for alkyne substrates, sequential condensation with amine followed by cycloaddition yielded the corresponding chromenoquinolines. All the aforementioned transformations were successfully accomplished under one-pot operation under aerobic conditions. Studies on mechanistic investigation revealed that the reaction followed a radical pathway.