The LANCA three-component reaction to highly substituted β-ketoenamides - versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

Synthetic transformation of 6-Fluoroimidazo[1,2-a]Pyridine-3-carbaldehyde into 6-Fluoroimidazo[1,2-a]Pyridine-Oxazole Derivatives: In vitro urease inhibition and in silico study

Purpose

Ulcer is a serious disease that is caused due to different bacteria and over usage of various NSAIDs which caused to reduce the defensive system of stomach. Therefore, some novel series are needed to overcome these issues.

Methods

Oxazole-based imidazopyridine scaffolds (4a-p) were designed and synthesized by two step reaction protocol and then subjected to urease inhibition profile (in vitro). All the newly afforded analogs (4a-p) were found potent and demonstrated moderate to significant inhibition profile.

Results

Particularly, the analogs 4i (IC₅₀ = 5.68 ± 1.66 μM), 4o (IC₅₀ = 7.11 ± 1.24 μM), 4 g (IC₅₀ = 9.41 ± 1.19 μM) and 4 h (IC₅₀ = 10.45 ± 2.57 μM) were identified to be more potent than standard thiourea drug (IC₅₀ = 21.37 ± 1.76 μM). Additionally, the variety of spectroscopic tools such as ¹H NMR, ¹³C NMR and HREI-MS analysis were employed to confirm the precise structures of all the newly afforded analogs.

Discussion

The structure-activity relationship (SAR) studies showed that analogs possess the substitution either capable of furnishing strong HB like -OH or had strong EW nature such as -CF₃ & -NO₂ groups displayed superior inhibitory potentials than the standard thiourea drug. A good PLI (protein-ligand interaction) profile was shown by most active analogs when subjected to molecular study against corresponding target with key significant interactions such as pi-pi stacking, pi-pi T shaped and hydrogen bonding.

Synthesis of 2,4,5-Trisubstituted Oxazoles from Copper-Mediated Benzylic sp3 C-H Aerobic Oxidative Annulation of Ketones and Amines via a Cascade Reaction

The functionalization of sp³ carbons is deemed challenging in synthetic organic chemistry yet has tremendous potential in producing potent organic compounds. A facile synthesis of 2,4,5-trisubstituted oxazoles through an oxidative, copper-catalyzed, and solvent-free annulation is described. Various arylated oxazoles were efficaciously synthesized at a mild temperature from readily available substrates under a molecular oxygen atmosphere. Preliminary mechanistic studies suggested that the reaction proceeds via an anionic-type mechanism and indicated the formation of a keto-imine intermediate. The reaction is notable for the abstraction of six hydrogen atoms, the functionalization of one sp² carbon and two sp³ carbons, and the formation of C-O and C-N bonds.

Recent Advances in the Synthesis of Oxazole-Based Molecules via van Leusen Oxazole Synthesis

Oxazole compounds, including one nitrogen atom and one oxygen atom in a five-membered heterocyclic ring, are present in various biological activities. Due to binding with a widespread spectrum of receptors and enzymes easily in biological systems through various non-covalent interactions, oxazole-based molecules are becoming a kind of significant heterocyclic nucleus, which have received attention from researchers globally, leading them to synthesize diverse oxazole derivatives. The van Leusen reaction, based on tosylmethylisocyanides (TosMICs), is one of the most appropriate strategies to prepare oxazole-based medicinal compounds. In this review, we summarize the recent advances of the synthesis of oxazole-containing molecules utilizing the van Leusen oxazole synthesis from 1972, aiming to look for potential oxazole-based medicinal compounds, which are valuable information for drug discovery and synthesis.