ChemInform Abstract: Novel Reactions of 5‐Chloro‐4‐formyl‐3‐methyl‐1‐phenylpyrazole with Active Methylene Compounds.

Abstract

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5-Chloropyrazole-4-carboxaldehydes as synthon in heterocyclic synthesis

“…El-atif et al [59] and Pawar [46] studied the reactivity of 4 with hydroxyl amine in pyridine, and they separate the oxazole derivative 124, whereas Holzer et al [58] reported that compound 4 reacted with hydroxylamine hydrochloride in ethanol to give the corresponding oxime 94, which does not undergo cyclization in either refluxing pyridine or sodium hydride to the corresponding pyrazolo [4,3-d]oxazole 124 (Scheme 27) [60].…”

“…Moreover, El Latif et al [63] reported that treatment of 4 with malononitrile 329a, ethylcyanoacetate 329b, cyanothioacetamide 329c, or cyanoacetamide 329d in ethanol/piperidine give the corresponding arylidenes 330. Shiba et al [60] have reported that treatment of 4 with malononitrile 329 (R = CN) in piperidine/ethanol to give 330 (R = CN) (Scheme 67).…”

“…While in ethanol/NaOH afforded the pyrazolone derivative 340c, base catalyzed condensation of ethyl acetoacetate with 330b in ethanol/piperidine afforded the pyranone derivative 341. Furthermore, treatment of 330b with cyclohexanone 337 in ethanol/piperidine gave a mixture from pyrazolone 3 and coumarine derivative 342 (Scheme 69) [60].…”

“…Condensation of 4 with ethyl glycinate hydrochloride 333 in boiling pyridine gave the pyrazole derivative 334 (Scheme 68)[60].…”

Convenient Synthesis and Characterization of Pyrazolones and Schiff Bases

“…S. GIRISHA AND B. KALLURAYA time with good yield. However, the reported procedure [12] of Knoevenagel condensation is carried out at high temperature. Further, at high temperature this Knoevenagel condensation resulted in the formation of bispyrazoles, whereas at room temperature it gave amino derivatives.…”