¹H and ¹³C NMR spectral assignments of nineteen 5‐(3,5‐dimethoxyphenyl)‐3‐(2‐methoxyphenyl)‐2‐pyrazoline derivatives

Abstract

Funding information Konkuk University 1 | INTRODUCTION 1,3-Diphenyl-2-propen-1-ones, also known as chalcones, belong to the class of plant-derived polyphenols. [1] They have a C6-C3-C6 skeleton and 2 six-membered aromatic rings that are connected via an α,β-unsaturated carbonyl group. [2] The hydrogen atoms can be substituted by various functional groups. [3] In addition to the two benzene rings, the α,β-unsaturated carbonyl group can be derivatized. [4] Because of their diverse biological activities, many such polyphenol derivatives have been reported. [5] In this study, we attempted to modify the α,β-unsaturated carbonyl group of the chalcones. In our previous study, in vivo and in vitro biological experiments, including xenograft assay, immunofluorescence microscopy, Western blotting, and Annexin V flow cytometry, [6] revealed that 2 0 ,3,5-trimethoxychalcone (Figure 1a) could selectively kill cancer cells. Hence, this compound was used as the basic skeleton to modify the α,β-unsaturated carbonyl group. Because compounds with a hydrazinecarbothioamide skeleton have been reported to exhibit anticancer activities against various cancer cells, including A549 lung cancer cells, MDA-MB-231 breast cancer cells, and HepG2 liver cancer cells, the oxygen atom of the of α,β-unsaturated carbonyl group was substituted with hydrazinecarbothioamide (Figure 1b). [7-9] Besides, hydrazine could be cyclized to form 4,5-dihydro-1H-pyrazole, 2-pyrazoline (Figure 1c). The 1-position of 2-pyrazoline was substituted with carbothioamide, carbaldehyde, ethanone, and thiazol-4-one. Several pyrazoline derivatives with carbothioamide and thiazol-4-one were modified further. Consequently, 19 novel 5-(3,5-dimethoxyphenyl)-3-(2-methoxyphenyl)-2-pyrazoline derivatives were designed and synthesized (Table 1). The nuclear magnetic resonance (NMR) spectral data and high-resolution mass spectrometry (HR/MS) data can be utilized for the structural identification and characterization of these pyrazoline derivatives bearing carbothioamide and thiazol-4-one moieties. Hence, we report the 1 H and 13 C NMR spectral data and HR/MS data here. 2 | EXPERIMENTAL 2.1 | Syntheses Nineteen novel derivatives were synthesized from the starting material, 2 0 ,3,5-trimethoxychalcone (designated as DPP23 in Scheme 1). [6] When 2 0 ,3,5-trimethoxychalcone was treated with hydrazinecarbothioamide (NH 2 CSNHNH 2), different products were formed depending on the reaction conditions. Open chain thiosemicarbazone (1) was obtained when 2 0 ,3,5-trimethoxychalcone was treated with B. Kim, S. Ahn, and Y. Lee contributed equally to this work.

The utilities of pyrazolines encouraged synthesis of a new pyrazoline derivative via ring closure of chalcone, for optimistic neurodegenerative applications

“…7-4. 22) ppm attributed to the adjacent and geminal protons H-C-CH2 moiety, which confirms the formation of a reduced ring of pyrazole [65,66]. The doubletdoublet peaks at (6.…”

“…The NMR spectra of the prepared chalcone and pyrazoline ligand were carried out at d6-DMSO solvent. The H NMR spectrum of chalcone showed no peaks in the shielding regions of aliphatic -CH3 moiety, which point to the processing of Claisen-Shmidt condensation between 2-Acetyl pyridine with 4-bromobenzaldehyde [65,66] The doubletdoublet peaks at 6. 5-7.…”