Three-component, one-pot synthesis of 2H-benzopyran derivatives

A protocol of three-component, one-pot synthesis of 2H-benzopyran derivatives is reported. Promoted by strong basic 1,8-diazabicyclo5.4.0undec-7-ene (DBU), salicylic aldehydes, sodium arylsulfinates and 3-bromoallyl-arylsulfones were reacted in the sequence of S-nucleophilic substitution, tandem Knoevenagel condensation/intramolecular oxa-Michael addition reactions to generate a series of 2,3-disubstituted-2H-benzopyran derivatives. Under optimized reaction conditions, 15 target products were prepared in 51%−86% yields. All products were newly synthesized and fully characterized by ¹H NMR, ¹³C NMR and HRMS. This method has the advantages such as high efficiency, mild reaction conditions and environmental friendliness.