The two individual absorption bands referring to NH stretching vibrations at 3345 cm − cm −1 proved the hydrazide formation. The FT-IR spectrum of hydrazide 4 disclosed the absorption band of C=O at 1665 cm −1 which indicated the transformation of ester linkage into hydrazide. The purity of the titled compounds was established from elemental analysis. The progress of reaction was monitored by TLC and structures of the synthesized compounds 6( a– t) were elucidated using different techniques including FT-IR, 1H NMR, 13C NMR spectroscopies and mass spectrometry (see Supplementary Materials). Hydrazinolysis of the synthesized ester ( 3) resulted in the formation of 2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetohydrazide ( 4), which was finally condensed with a variety of aromatic aldehydes 5( a– t) in acidic conditions to afford titled N-acylhydrazones 6( a– t) in 82–99% yield. 6-Methyl-1 H-pyrazoloquinoline ( 2) was converted to methyl 2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetate ( 3) by reacting it with methyl chloroacetate under S N2 conditions.

The ratio of both conformers was also calculated and E (C=N) (N-N) syn-periplanar conformer was established to be in higher percentage in equilibrium with the E (C=N) (N-N) anti-periplanar form.Ģ-Chloro-6-methylquinoline-3-carbaldehyde ( 1) was used as precursor for the synergism of quinoline ring with pyrazole scaffold to afford 6-methyl-1 H-pyrazoloquinoline ( 2) after cyclocondensation with hydrazine monohydrate. NMR spectra revealed the presence of N’-(benzylidene)-2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetohydrazides as a mixture of two conformers, i.e., E (C=N)(N-N) synperiplanar and E (C=N)(N-N) antiperiplanar at room temperature in DMSO- d 6. The stereochemical behavior of 6( a– t) was studied in dimethyl sulfoxide- d 6 solvent by means of 1H NMR and 13C NMR techniques at room temperature. Structures of the synthesized compounds were established by readily available techniques such as FT-IR, NMR and mass spectral studies. The hydrazinolysis of 3 followed by the condensation of resulting 2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetohydrazide ( 4) with aromatic aldehydes gave N-acylhydrazones 6( a– t). 2-Chloro-6-methylquinoline-3-carbaldehyde (1) afforded 6-methyl-1 H-pyrazoloquinoline ( 2), which upon N-alkylation yielded 2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetate ( 3). Twenty new 6-methyl-1 H-pyrazoloquinoline substituted N-acylhydrazones 6( a– t) were synthesized from 2-chloro-6-methylquinoline-3-carbaldehyde ( 1) in four steps. In this article, a synthesis of N’-(benzylidene)-2-(6-methyl-1 H-pyrazoloquinolin-1-yl)acetohydrazides and their structural interpretation by NMR experiments is described in an attempt to explain the duplication of some peaks in their 1H- and 13C-NMR spectra.

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