Design, Synthesis, Characterization, and Antimicrobial Screening of Novel Indazole Bearing Oxadiazole Derivatives

Ethyl 2‐(2,6‐dioxocyclohexyl)‐2‐oxoacetate was prepared by reacting cyclohexane‐1,3‐dione ( 1 ) and diethyl oxalate ( 2 ) with the help of sodium ethoxide in ethanol at 0–5°C. Subsequent treatment of ethyl 2‐(2,6‐dioxocyclohexyl)‐2‐oxoacetate with hydrazine hydrate in ethanol resulted into ethyl 4‐oxo‐4,5,6,7‐tetrahydro‐2 H ‐indazole‐3‐carboxylate while without solvent in excess hydrazine hydrate on reflux resulted into 4‐oxo‐4,5,6,7‐tetrahydro‐2 H ‐indazole‐3‐carbohydrazide ( 3 ). The synthesis of novel indazole bearing oxadiazole derivatives (ODZ 01 to 16) has been achieved by the reaction of hydrazide of 2 H ‐indazole ( 3 ) with acid ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p ) in the presence of POCl 3 , and the antimicrobial activity of synthesized novel compounds has been studied.