Enantioselective [5 + 1] cycloaddition of sulfur ylides and vinylethylene carbonates via synergistic palladium/chiral phosphonic acid catalysis

An effective method for the synthesis of dihydropyrans through synergistic palladium and chiral phosphonic acid catalysis was reported. This protocol proceeded under mild reactions and provided dihydropyrans in up to 87% yield and up to 97% ee. Meanwhile, various derivations such as oxidation, Wittig-reaction, reductions, nucleophilic substitution, and Baeyer–Villiger were accomplished to furnish interesting compounds. To gain insight into the reaction mechanism, nonlinear relationship experiments and Hammett plot experiments were carried out. In addition, a range of products (3i, 4b, 4f, 4g, and 4j) accessible from this method exhibit various anti-inflammatory activities on NO and ROS inhibition.