Rhodium‐Catalyzed Regioselective C—O and C—C Bonds Formation of 3‐oxopent‐4‐enenitriles with Alkynes for the Synthesis of Polysubstituted 2H‐pyrans

Comprehensive SummaryThe rhodium‐catalyzed C—H bond activation and cyclization of 3‐oxopent‐4‐enenitriles with alkynes proceed efficiently. Various 2H‐pyrans with multiple substituents are achieved in good yields through regioselective formation of C—O and C—C bonds. Transformations involving hydroxy‐alkynoates resulted in products with a furo[3,4‐b]pyran skeleton via further intramolecular ester exchange processes. Different from the traditional “1‐oxatrienes pathway”, this method for the synthesis of useful 2H‐pyrans possesses certain highlights in terms of readily available substrates, stable and easily derivatized products, gentle and convenient operation process, and step and atom economy.