Double 1,4-addition of (thio)salicylamides/thiosalicylic acids with propiolate derivatives: a direct, general synthesis of diverse heterocyclic scaffolds
ring-closure procedure to prepare a range of diverse heterocycles has been developed. In this transformation, a variety of substituted (thio)salicylamides and thiosalicylicacids occured double 1, 4-additions reaction with propiolate derivatives in the presence of inorganic base (K3PO4), as a result, benzothiazinones, benzoxazinones and benzoxathiinones were prepared in good to excellent yields respectively