Facile and Efficient One-Pot Synthesis of Highly Functionalized Thieno[2,3b]thiopyran-4-ones from b-Keto e-Xanthyl Phosphonates

Abstract : Synthesis of various functionalized thieno[2,3-b]thiopyran-4-ones from readily available β-keto ε-xanthyl phosphonates has been accomplished by combining a Horner−Wadsworth−Emmons olefination with a base-induced intramolecular domino cyclization/thio-Michael addition. The use of cyclic ketones in this transformation allowed a facile access to novel spiro-type thieno[2,3-b]thiopyran structures.