The Reactions of 2-Arylacetylene-1-sulfonamides with Heterocumulenes

Abstract

Abstract The syntheses of new heterocyclic compounds by the reaction of 2-arylacetylene-1-sulfonamides 1, (Z)-β-bromo- 12 or (Z)-α-chloro-β-styrenesulfonamides 13 with heterocumulenes are described. Weak base treatment of ureas R1C6H4C≡CSO2NHC(=O)NHR2 prepared from 1 and isocyanates gave 2-amino-6-aryl-1,4,3-oxathiazine 4,4-dioxides, whereas strong base treatment of the ureas afforded 3-oxo-4,5-diphenyl-2,3-dihydro-1,2,4-thiadiazine 1,1-dioxides where R2 is a phenyl group. The thiadiazines were also prepared by the strong base treatment of N-((Z)-α-bromo- or (Z)-β-chlorostyrylsulfonyl)-N′-phenylureas. The reaction of 1,12, or 13 with isothiocyanates in the presence of weak base gave 3-amino-5-aryl-1,4,2-dithiazine 1,1-dioxides, but the major products produced were 3-amino-5-benzylidene-1,4,2-dithiazole 1,1-dioxides when 12a was treated with isothiocyanates in the presence of strong base. The reaction of 1 with carbon disulfide and dimethyl sulfate in the presence of 5 M NaOH afforded 3-methylthio-5-benzylidene-1,4,2-dithiazole 1,1-dioxide with a small amount of 3-methylthio-5-aryl-1,4,2-dithiazine 1,1-dioxide. A mixture of both isomers was also prepared from 12a. Possible mechanisms for the formation of the heterocycles from 1, 12, or 13 are suggested.