Transition‐Metal‐Free One‐Pot [3+3] Heteroannulative Coupling of Thioamides with Epichlorohydrin: Access to Diverse 1,3‐Thiazinanes

Abstract An operationally simple and efficient cascade approach to access a series of 1,3‐thiazinanes has been developed through intermolecular [3+3] heteroannulative coupling employing β‐ketothioamide as a C1 N1S1 unit and epichlorohydrin as a C3 unit at room temperature for the first time. The reaction proceeds by nucleophilic attack of thiocarbonyl sulfur to less hindered primary carbon of oxirane followed by sequential intramolecular N‐cyclization and dehydrochlorination enabling the coupling by cleavage of C−O bond and formation of two new C−S and C−N bonds in one stretch. This protocol not only avoids potential toxicity and tedious work up procedures, but also features open atmosphere, good to high yields, gram‐scalability, and easy performance from inexpensive, readily available starting materials under transition‐metal‐free conditions. A probable mechanism for the formation of 1,3‐thiazinanes has been suggested.