Abstract
Diazonium chlorides of 5-amino-3-methypyrazole 1a and 5-amino-4-phenylpyrazole 1b coupled with 1,3-indanedione 2 and led to the formation of acyclic hydrazone 3a and a cyclic product indenopyrazolotriazine 4b respectively. Cyclization of the hydrazone 3a by boiling in acetic acid afforded the corresponding 4a. The hydrazone 3a reacted with malononitrile in boiling ethanol in the presence of piperidine and gave indeno[2,1-c]pyridazine-4-carbonitrile derivatives 5a,b. Also, coupling of 6 with aryl diazonium chlorides gave the corresponding indenopyridazine derivatives 8a-e. Acetylation, benzoylation and hydrolysis of compound 8a afforded the corresponding substitution products 10-12, respectively. The structures of the newly synthesized compounds were established on the basis of chemical and spectral evidences.
Highlights
As a part of our program aimed to developing synthesis of functionally substituted heteroaromatics from readily starting materials [1,2,3,4,5], we have previously reported the synthesis of 4,5-dihydrospiropyrazole-indane-1, 3-diones [6] and thiadiazoline derivatives [7] via reaction of hydrazonoyl halides with 2-arylidene indane-1, 3-dione and indane-1,3-dione-2-thiocarboxanilides, respectively
In conjunction of this work we intended here to utilize the known coupling reaction [8] of diazotized heterocyclic amines with active methylene compounds, using 1,3-indanedione as an active methylene compound with unreported heterocyclic amines to synthesize some new derivatives of the title compounds with anticipated biological activities
Our interest in synthesis of some novel indeno[1,2-e]pyrazolo[5,1-c]-1, 2,4-triazines, is owing to the fact that pyrazolo[5,1-c]-1, 2,4-triazines were reported to have remarkable cytotoxic activity against colon, breast and lung carcinoma cells [9], some derivatives show to have selective cytotoxicity in hypoxic and in normoxic conditions [10], hetarylazo derivatives were classified as diazo dyes [11]
Summary
As a part of our program aimed to developing synthesis of functionally substituted heteroaromatics from readily starting materials [1,2,3,4,5], we have previously reported the synthesis of 4,5-dihydrospiropyrazole-indane-1, 3-diones [6] and thiadiazoline derivatives [7] via reaction of hydrazonoyl halides with 2-arylidene indane-1, 3-dione and indane-1,3-dione-2-thiocarboxanilides, respectively. Our interest in synthesis of some novel indeno[1,2-e]pyrazolo[5,1-c]-1, 2,4-triazines, is owing to the fact that pyrazolo[5,1-c]-1, 2,4-triazines were reported to have remarkable cytotoxic activity against colon, breast and lung carcinoma cells [9], some derivatives show to have selective cytotoxicity in hypoxic and in normoxic conditions [10], hetarylazo derivatives were classified as diazo dyes [11]. Indeno-fused pyridazines have been reported to show inhibition potency toward monoamine oxidase-B (MAO-B) [12,13,14] and to display binding affinity for central benzodiazepine receptors [15]
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