Synthesis and transformations of chloropyrazolealdehydes

A Convenient Synthesis of Some Pyrazolinone and Pyrazole Derivatives

“…Reaction of compound 1 with dimethylformamide in the presence of phosphorus oxychloride under Vilsmeier-Haack reaction conditions 11 gave 5-chloro-1-phenyl-3-pyridin-4-yl-1H-pyrazole-4-carbaldehyde (4), which was subjected to react with different reagents such as hippuric acid in the presence of acetic anhydride and sodium acetate to give 4-(5-chloro-1-phenyl-3-pyridin-4-yl-1H-pyrazol-4-ylmethylene)-2-phenyl-4H-oxazol-5-one (5). The oxidation of the formyl group in compound 4 by potassium permanganate under the condition of phase-transfer catalysis (PTC) 12 (6), which on esterification with ethyl alcohol afforded the corresponding ethyl ester 7 (Scheme II). Treatment of compound 4 with excess sodium azide in DMSO at 110°C gave the two products 5-azido-1-phenyl-3pyridin-4-yl-1H-pyrazole-4-carbaldehyde (8) and 5-hydroxy-1-phenyl-3-pyridin-4-yl-1H-pyrazole-4-carbonitrile (9).…”

Synthesis of substituted 3‐phenyl‐6h‐pyrazolo[4,3‐d]isoxazoles from corresponding 4‐benzoyl‐5‐hydroxypyrazoles

“…After stirring at room temperature for 20 hours water (8 ml) was added and the mixture was left for additional 3 hours. The precipitated solid was collected by filtration, washed with water and dried to afford 330 mg (95%) of colorless needles, mp 163-165°(lit [39] A mixture of 5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-carbaldehyde (5e) (221 mg, 1 mmole) and hydroxylamine hydrochloride (114 mg, 1.64 mmoles) in ethanol (3 ml) was 306…”

Adducts of Zinc(II) Acetylacetonate with Various Aminoquinolines: Synthesis, Structure and Luminescence

“…In these molecular systems, aminoquinoline moieties act as emitters, while zinc formylpyrazolonate part is responsible for thermal and chemical stability. Synthesis of this zinc formylpyrazolonate is quite expensive and involves the use of toxic components . Therefore, it was decided to replace it with more synthetically available and “green” zinc(II) acetylacetonate.…”