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 (α
and β carbons or β and γ 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.