A facile synthesis of novel biologically active 4-hydroxy-N′-(benzylidene)-2H-benzo[e][1,2]thiazine-3-carbohydrazide 1,1-dioxides

A novel series of potentially biologically active 4-hydroxy- N ′-(benzylidene)-2 H -benzo[ e ][1,2]thiazine-3-carbohydrazide 1,1-dioxides were synthesized starting from ultrasonic mediated N-alkylation of sodium saccharin with methyl chloroacetate. Ring expansion of methyl(1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3 H )-yl)acetate followed by its hydrazinolysis afforded 4-hydroxy-2 H -1,2-benzothiazine-3-carbohydrazide 1,1-dioxide which was reacted in a straight forward manner with various benzaldehydes in an ultrasonic bath to get the title compounds. All of the synthesized compounds were subjected to preliminary evaluation for their antibacterial and DPPH radical scavenging activities.