2-Substituted indazoles.: Synthesis and antimicrobial activity

2-Isothiocarbamoyl substituted fused pyrazolines and their S-alkvl derivatives were prepared as potentially antimicrobial agents. Conventional methods were used to synthesize the novel derivatives starting from cyclic unsaturated ketones and thiosemicarbazide under acidic catalyst. These cyclizations yielded only one diastereoisomer of 3-H, 3a-H cis. The alkylations were performed applying alkyl halides. The structures of the new compounds, including configurations and conformations, were elucidated by NMR spectroscopy, also making use of 2D-HSC, DEFT and DNOE measurements. The S-alkyl derivatives were evaluated for activity against Gram-negative and Gram-positive bacteria and their in vitro toxicity was determined on HeLa cells. The structure-activity relationship was also studied. (C) 1999 Editions scientifiques et medicales Elsevier SAS.