A case study of the iodine‐mediated cyclization of C2′‐OH‐ and C2‐OH‐chalcones toward the synthesis of flavones: Reinvestigation of the mechanisms

Synthesis of flavones from chalcones via the iodine‐mediated cyclization required at least one hydroxy group at their C2′‐positions. On the contrary, the ring oxidative cyclization from C2‐OH‐chalcones under the same condition was unusual and reported only once. We evaluated the aforementioned method and found different results. The mechanisms in detail were discussed. The iodine‐mediated cyclization of C2′‐OH‐chalcones to synthesize flavones is a very popular method. A reported procedure to bring our attention was starting from C2‐OH‐chalcones to form flavones. We reinvestigated this strategy and found different results. The detailed mechanisms were discussed.