NaHSO₄/SiO₂ catalyzed generation of o-quinone/ o-thioquinone methides: synthesis of arylxanthenes/ arylthioxanthenes via oxa-6π-electrocyclization

ortho-Quinone methides, very reactive transient intermediates, are utilized successfully in synthesizing complex organic molecules of natural and biological significance. Among several synthetic protocols, the acid catalyzed generation of ortho-quinone methides from suitably substituted phenols is a promising method for further exploitation in organic synthesis. Such an interesting reactive species is conveniently employed in the synthesis of...