Synthesis and X-ray Crystal Structure of New Substituted 3-4′-Bipyrazole Derivatives. Hirshfeld Analysis, DFT and NBO Studies

Ahmed T A Boraei,Ahmed A M Sarhan,Abdullah Mohammed Al-Majid,Saied M Soliman,Assem Barakat,Matti Haukka

doi:10.3390/cryst11080953

Abstract

A new compounds named 3-4′-bipyrazoles 2 and 3 were synthesized in high chemical yield from a reaction of pyran-2,4-diketone 1 with aryl hydrazines under thermal conditions in MeOH. Compound 2 was unambiguously confirmed by single-crystal X-ray analysis. It crystalizes in a triclinic crystal system and space group P-1. Its crystal structure was found to be in good agreement with the spectral characterizations. With the aid of Hirshfeld calculations, the H…H (54.8–55.3%) and H…C (28.3–29.2%) intermolecular contacts are the most dominant, while the O…H (5.8–6.5%), N…H (3.8–4.6%) and C…C (3.0–4.9%) are less dominant. The compound has a polar nature with a net dipole moment of 6.388 Debye. The BD(2)C31-C32→BD*(2)N4-C34 (27.10 kcal/mol), LP(1)N5→BD*(2)C31-C32 (36.90 kcal/mol), BD(1)C32-C34→BD*(1)C18-C31 (6.78 kcal/mol) and LP(1)N4→BD*(1)N5-C31 (7.25 kcal/mol) are the strongest π→π*, n→π*, σ-σ* and n→σ* intramolecular charge transfer processes, respectively.

Highlights

Pyranones are examples of ester-functional heterocyclic molecules which have been employed as a synthon for several targeted organic compounds [1]
These synthetic pyranones have been reported to have several applications related to medicine, including HIV protease inhibitors [2], anticonvulsants [3], antitumor [4,5], antifungal [3], and antimicrobial [6] agents, and as plant-growth regulators [2,7]
Many approaches have been reported for the synthesis of pyrazoline scaffolds [20,21,22,23,24,25,26]

Summary

Introduction

Pyranones are examples of ester-functional heterocyclic molecules which have been employed as a synthon for several targeted organic compounds [1]. Some other naturally occurring pyranones were reported to have interesting actions against bacteria, and have cytotoxic effects (e.g., Marin natural product, Pectinatone) [8] Another representative example works against inflammation and rheumatism (e.g., Bufalin) [9], and many others such as Pentylpyran-2-one [10] and Griseulin [11,12] exhibited antibiotic and mosquitocidal effects, respectively. Heterocycles comprising five-membered rings with two adjacent nitrogen atoms are called pyrazoles, and these pharmacophore-containing heterocycles have been shown to have several therapeutic applications They were reported to have interesting actions against different diseases, including cancer, inflammation, and bacterial infection, and can be used as analgesic and antidepressant agents [16,17,18]. One representative common approach is a reaction of carbonyl compounds with hydrazines under thermal conditions [27], in addition to other reported methods for the synthesis of pyrazolines scaffold, such as the metal catalyzed approach [28]

Methods

Results

Conclusion