Synthesis of 2-Aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolobenzothiazoles and their 3-Aryl- Isomers

Article abstract of DOI:10.1007/BF00807167

Condensation of 3-aryl-5-thio-1,2,4-4H-triazoles (2a-i) and 2-bromodimedone (3) in THF/benzene gave 2-aryl-6,6-dimethyl-8-oxo-5a-hydroxy-5,5a,6,7,8,8a-hexahydro-1,2,4-4H-triazolo<3,2-b>benzothiazoles (5a-i).There were also obtained by a one step synthesis on heating a mixture of dimedone, NBS, and 2a-i in benzene containing a trace of benzoyl peroxide.Thermal dehydration of 5a-i in PPA/anhydrous ethanol yielded the corresponding 2-aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolo<3,2-b>benzothiazoles (6a-i).The formation of <3,4-b> fused isomers (4a-i) during the reaction of 2 with 3 was ruled out by an unambiguous synthesis of 8a-i.Antibacterial screening of selected compounds against Escherichia coli and Staphylococcus aureus was not encouraging. - Keywords: 3-Aryl-5-thio-1,2,4-4H-triazoles; Dimedone; 2-Bromodimedone; Cyclic hydroxy intermediate; Isomeric<3,2-b> and <3,4-b>benzothiazoles