Unravelling the synthetic and therapeutic aspects of five, six and fused heterocycles using Vilsmeier–Haack reagent

Abstract

The aim of this review is to encapsulate the synthetic protocols and medicinal aspects of a wide range of heterocyclic compounds using the Vilsmeier–Haack (V. H.) reagent.

Synthesis of pyrazolo-azepinone derivatives via Morita–Baylis–Hillman chemistry as potent antimicrobial agents

“…The hydrazone derivatives 3a–g were subsequently subjected to the Vilsmeier–Haack reaction in the presence of DMF-POCl 3 which easily furnished the desired 4-formyl-pyrazole-3-carboxylates 4a–g at room temperature in 86–96% yields (Scheme 1). 14…”

Development in the Synthesis of Bioactive Thiazole-Based Heterocyclic Hybrids Utilizing Phenacyl Bromide

“…This compound finds extensive applications in pharmacology, serving as a herbicidal, antibacterial, antiviral, antihistaminic, and antiallergic agent (Figure 22). 75 Jadav et al 76 proficiently conducted the synthesis of a series of pyrazoline-thiazole linked pyridine hybrids 51a−51t. This synthetic protocol entailed the reaction between pyrazoline derivatives 50 and phenacyl bromide 7 in ethanol, resulting in good yields within reaction duration of 30 to 45 min.…”

“…This compound finds extensive applications in pharmacology, serving as a herbicidal, antibacterial, antiviral, antihistaminic, and antiallergic agent ( Figure 22 ). 75 …”

3-(2-Chloroethoxy)-1-(4-methoxyphenyl)-1H-pyrazole-4-carbaldehyde

“…Supplementary Materials: 2D MDL molfile of Compound 2, Figure S1: 1 H NMR spectrum of compound 2; Figure S2: 13 C NMR spectrum of compound 2; Figure S3: 1 H-1 H NOESY spectrum of compound 2; Figure S4: 13 C NMR/DEPT 135 spectra of compound 2; Figure S5: The overlaid 1 H- 13 C HSQC/HMBC NMR spectra of compound 2; Figure S6: 1 H- 15 N HMBC spectrum of compound 2;…”

“…The Vilsmeier-Haack reaction is a useful tool for the formylation of aromatic and heterocyclic compounds, such as pyrroles, imidazoles, pyrazoles, etc. [1]. It has been shown that variously substituted pyrazole derivatives can be transformed into condensed pyrazolo [3,4b]pyridines, pyrazolo[1,5-a]-, and pyrazolo [3,4-d]pyrimidines through the Vilsmeier-Haack reaction [2,3].…”