Synthesis, Properties, and Reactions of 1H-Indazol-3-ols and 1,2-Dihydro-3H-indazol-3-ones

Synthesis and Evaluation of 1,1′‐Hydrocarbylenebis(indazol‐3‐ols) as Potential Antimalarial Drugs

“…According to the literature data, alkylation of the 2-substituted indazolin-3-ones affords only the corresponding 1,2-disubstituted derivatives. [3,15,16] The prepared indazoles were tested as inhibitors of ferri-A C H T U N G T R E N N U N G protoporphyrin IX biocrystallization; [11] hydrocarbylenebis(indazol-3-ols) (30-33, 36, 37) were, in most cases, more active than the control (chloroquine diphosphate, IC 50 = 28 mm), but similar in activity to that of the lead compound 5 (Table 1). Only ethylene derivative 34 and o-xylylene derivative 38 were inactive, while tetramethylenebis(indazol-3-ol) (35) could not be evaluated owing to low solubility.…”

“…These compounds were subsequently evaluated as inhibitors of biocrystallization of ferriprotoporphyrin IX (heme) to hemozoin, a Plasmodium detoxification specific process. Most bis(5-nitroindazol-3-ols) were good inhibitors, however, a denitro analogue (38), the intermediate bis(3-alkoxyindazoles) (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) as well as bis(indazolin-3-ones) (39-42) were not active, showing the importance of the NO 2 and OH groups in the inhibition process.…”

1,5-Disubstituted Indazol-3-ols with Anti-Inflammatory Activity

“…Indazol-3-ols are synthesized by common procedures [5,6] . We used 5-substituted 2-halogenobenzoic acids (3) and hydrazine hydrate as starting materials which were heated to give hydrazino benzoic acid derivatives.…”

“…In all cases the IR and NMR spectra indicated the presence of the 3-hydroxy group and not a carbonyl group (no carbonyl band at about ν ≈ 1700 cm -1 s ). [5] . (5) was prepared by the method of Pfannstiel et al [6] .…”

“…Compounds 6-50 were prepared by similar methods as reported previously [5] . Typical procedures are described in the following:…”