Phase Transfer Reagent Promoted Tandem Ring-Opening and Ring-Closing Reactions of Unique 3‑(1-Alkynyl) Chromones

A phase transfer reagent promoted tandem ring-opening and ring-closing reaction of 3-(1-alkynyl) chromones has been developed. This process remarkably generates functionalized 3-acyl-2-substituted chromones. Interestingly, when 3-(hepta-1,6-diyn-1-yl)­chromone derivatives are applied, a novel tetracyclic chromone scaffold can be obtained by a further intramolecular 4 + 2 cyclization