Structurally Dependent Acid‐Catalyzed Cyclization of (het)arylbisallomaltol Derivatives

ABSTRACT For the first time, in the present communication we studied intramolecular cyclization of (het)arylbisallomaltols under the action of acidic reagents. It was shown that the presented transformation provides efficient access to structurally diverse heterocyclic systems, with the product outcome determined by the nature of the (het)aryl substituent in the starting materials. In most cases, the investigated process affords previously unreported 4 H ‐dipyrano[3,2‐ b :2′,3′‐ e ]pyran‐4,6(10 H )‐diones via the binding of hydroxyl groups of two allomaltol units. At the same time, the presence of active functional groups in the (het)aryl moiety alters the reaction pathway, resulting in the formation of condensed pyrano[3,2‐ b ]pyran‐4(8 H )‐ones. These findings enabled the development of general synthetic strategies for diverse polycyclic pyran‐4‐one‐containing frameworks. Additionally, the attempt to synthesize a benzimidazolyl‐containing bisallomaltol unexpectedly led to the formation of benzo[4,5]imidazo[1,2‐ a ]pyridin‐1(5 H )‐one derivative. The key representatives of the obtained products were unambiguously confirmed by X‐ray analysis.