Base-promoted [4 + 2] cycloaddition of alkynyl 1,3-dithianes and chalcones to access highly substituted pyran derivatives

Polysubstituted pyrans are fundamental scaffolds in organic and medicinal chemistry, widely recognized for their roles in bioactive molecules and advanced materials. This study presents a base-promoted [4 + 2] cycloaddition reaction of alkynyl 1,3-dithianes with chalcones, providing an efficient and regioselective approach for the construction of highly functionalized pyran derivatives. The method demonstrates excellent substrate tolerance and compatibility, enabling the synthesis of complex pyran frameworks under mild conditions with high atom economy.