Lewis Acid‐Catalyzed Intramolecular [3+2] Cycloaddition of Cyclopropane 1,1‐Diesters with Alkynes for the Synthesis of Cyclopenta[c]chromene Skeletons

An efficient method to construct cyclopenta[c]chromene skeletons by Lewis acid-catalyzed intramolecular [3+2] cycloaddition of cyclopropane 1,1-diesters with alkynes is presented. Two new fused cycles can be formed in one step in moderate to excellent yields (up to 94 %), and the products can be converted into bioactive barbituric acid derivatives (1) under simple reaction conditions.