Access to Functionalized 1,4-Oxathiines through [3 + 3] Annulation of Dicyanoepoxides with Pyridinium
Abdulrahman Al Abdali1, Yazdanbakhsh Lotfi Nosood1, Negin Fattahi Ghahnavieh1
1Natural and Medical Sciences Research Center, University of Nizwa, P.O. Box 33, Birkat Al Mauz, Nizwa 616, Sultanate of Oman.
Abstract:
A metal- and base-free [3 + 3] annulation of readily accessible dicyanoepoxides and pyridinium 1,4-zwitterionic thiolates has been developed. The protocol enables the efficient synthesis of highly substituted 1,4-oxathiine derivatives under mild conditions and in green media with a broad substrate scope. Furthermore, the synthetic utility of the method was demonstrated through a post-transformation involving a ring-opening/recyclization sequence with primary amine derivatives, furnishing a range of 1,4-thiazine scaffolds.
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