One‐Pot Synthesis of N,N‐Disubstituted (Z)‐4‐(Halomethylidene)‐4H‐3,1‐benzothiazin‐2‐amines from 2‐(2,2‐Dihaloethenyl)phenyl Isothiocyanates and Secondary Amines

We have developed a one-pot procedure for the preparation of N,N-disubstituted (Z)-4-(halomethylidene)-4H-3,1-benzothiazin-2-amines 3 from 2-(2,2-dihaloethenyl)phenyl isothiocyanates 1, easily accessible from known 2-(2,2-dihaloethenyl)benzenamines by a three-step sequence, and secondary amines. Thus, the isothiocyanates 1 react with secondary amines to afford the corresponding thiourea derivatives, of which the treatment with NaH provides the desired products.