Substrate-Controlled Domino Reactions of Crotonate-Derived Sulfur Ylides: Synthesis of Benzothiophene Derivatives

Substrate-controlled domino reactions between thioaurones or their analogues and crotonate-derived sulfur ylides were developed and produced a broad spectrum of benzothiophene-fused pyran derivatives, substituted chromene derivatives. In these reactions, crotonate-derived sulfur ylides acting as two-carbon synthons (a and beta carbons or beta and gamma carbons) in annulation reactions are reported for the first time. These investigations nicely complement and expand previously studied reactions of crotonate-derived sulfur ylides. In addition, reaction mechanisms for these domino reactions are proposed, one of which is supported by DFT calculations.