I (2) /DTBP Promoted Synthesis of C3-Carbonylated Imidazopyridines from Chromones and 2-Aminopyridines via (3+2) Cycloaddition

An I-2/DTBP-promoted (3+2) cycloaddition reaction of 2-aminopyridines and chromones is reported. The work provides a simple and efficient approach to access imidazopyridines scaffold in moderate to good yields. I-2/DTBP as an initiator and oxidant was used to realize the tandem (3+2) cycloaddition/oxidative aromatization. Available starting materials, excellent functional-group tolerance, potential drug activity of the products, and application in production on a gram scale are advantageous features of this strategy. Moreover, the obtained products provide a key active fragment for the synthesis of cabozantinib analogues, which has the potential to be developed as an anticancer agent.