Current Organic Synthesis - Volume 19, Issue 6, 2022

Regarding the critical role of amyloid-β plaques in the pathogenesis of Alzheimer's disease, a series of aminoimidazo[1,2-a]pyridine derivatives were designed and synthesized as potential anti-BACE1 agents targeting the production of amyloid-β plaques. In vitro biological results demonstrated that compounds 7b and 7f exhibited the best inhibitory potency against BACE1 with IC50 values of 22.48 ± 2.06 and 30.61 ± 3.48 μM, respectively. Also, the ligandprotein docking evaluations revealed that compounds 7b and 7f could effectively bind with the different pockets of BACE1 through different interactions with the residue of the active site. The results of current studies underline the potential role of aminoimidazo[1,2-a] pyridine-containing pyrazole derivatives for developing novel BACE1 inhibitors.

Aims: The aim of this present work was to design and establish an efficient synthesis of new thienyl pyrazolo[1,5128;a] pyrimidines using an environmentally friendly reaction solvent. Further, the newly synthesized compounds were evaluated for antimicrobial activity. Materials and Methods: A series of thienyl pyrazolo[1,5128;a] pyrimidines have been synthesized by the condensation reaction of 4128;(4’128;chloro128;phenylazo)128;5128;amino pyrazole with α, β128; unsaturated carbonyl composites (chalcones) using NaOH in polyethylene glycol- 400 as a green reaction solvent. The dissemination technique recommended by the National Clinical Laboratory Standards Committee was used to study the antimicrobial activities of synthesized compounds. Results and Discussion: Polyethylene glycol-400 prompting an efficient synthesis of thienyl pyrazolo[1,5128;a] pyrimidines have been discussed. Excellent yields of the products were obtained in a shorter reaction time using PEG 400 as a green reaction solvent. The reaction solvent was recovered and reused without the loss of its activity. The synthesized compounds have shown interesting antibacterial activity. Hydroxyl and halo substitution with thienyl moiety emerged as an active antibacterial and antifungal study. Conclusion: The advantage of this methodology is that it incorporates the green method, has excellent yields, easy workup, avoids toxic solvents, and an expensive catalyst. The new dimension pyrazolo[1,5-a] pyrimidine derivatives with thienyl moiety exhibit promising anti-microbial activity.

Background: Thiazole-containing compounds are widely found in natural products as well as synthetic sources. Many thiazole-based compounds possess a broad spectrum of bioactivities, and some of them are well-known drugs in the markets. The use of thiazole derivatives in other fields such as organic materials, cosmetics, and organic synthesis has also been widely reported. Due to a wide range of applicability, the synthesis of thiazole-containing compounds has attracted extensive interest from chemists, and many studies in the synthesis of thiazole skeleton have been reported recently. Objective: This review article will discuss recent studies in the synthesis of thiazoles (from2012). Besides the well-established Hantzsch thiazole synthesis, a large number of novel methods have been developed for the synthesis of thiazole derivatives. In most cases, reaction mechanisms have also been described. Conclusion: The synthesis of thiazole derivatives has drawn great attention from chemists, and many studies in the synthesis of these heterocycles have been reported recently. The classical method, the Hantzsch thiazole synthesis has received great research interest from chemists. Moreover, many new methods have been established to synthesize thiazole-derived compounds. Unquestionably, more and more approaches to access thiazole skeleton will appear in the literature. The application of well-established thiazole synthesis methods to the synthesis of drugs, organic materials, and natural products will almost certainly be studied.

Rational design and synthesis of novel compounds with both effectivity and safety properties have always been a formidable task in the development of drugs. Oxadiazoles are heterocyclic bioscaffolds occurring as motifs in drug-like molecules. This review article highlights comprehensive and systematic information of compounds containing 1,2,4-oxadiazoles and 1,3,4-oxadiazole rings. The routes for the synthesis of the oxadiazoles have also been discussed, along with their biological significance. This review may help researchers in rational design for the development of effective and less toxic 1,3,4- oxadiazole based compounds. We present an informative review about the drugs derived from oxadiazole rings and their therapeutic application as well as a brief remark on the future development prospects.

Objective: The current objective was to synthesize biologically active Isatin derivatives. For this purpose, six (06) chemical entities of Isatin derivatives such as 3a-3c and 4a-4c were synthesized from Isatin substrate. Methods: The pure compounds were characterized with the help of ¹H-NMR, FT-IR, EIMS spectroscopic techniques. The synthesized amines 3a-3c and hydrazones 4a-4c were evaluated for their toxicity potential with the help of brine shrimp bioassay. Results: The obtained results revealed that 3c exhibited promising toxicity (LD50 = 1.03 × 10^-5 M) against Artemia salina. The pure chemical entities such as compounds 3a-3c and 4a-4c were evaluated against four Gram-negative (E. coli, P. aeruginosa, S. typhi, S. flexneri) and two Gram-positive (B. subtilis, S. aureus) bacteriae. The compound 3a displayed significant activity against two bacterial strains; i.e. P. aeruginosa, S. typhi, compound 3c demonstrated significant activity against P. aeruginosa. Compound 4b was the most active against S. typhi, displaying a greater diameter of the growth of inhibition zone (GIZ) than the standard drug. Compound 4c exhibited significant activity against P. aeruginosa and S. typhi. Compounds 3a-3c and 4a-4c exhibited moderate to significant antibacterial activity against three out of five strains. Only Compound 3c revealed promising toxicity (LD50 = 1.03 × 10^-5 M) against Artemia salina. Antifungal studies of the compounds 3a-3c and 4a-4c against six fungal cultures; T. longifusus, C. albicans, A. flavus, M. canis, F. solani, and C. glabrata. All the compounds were active against one or more pathogens having inhibition (10- 90 %). Compound 3a exhibited significant inhibition i.e. 90 % against M. canis, 70 % against T. longifusus, compound 4b further displayed significant inhibition (90 %) against A. flavus and thus proved to be the most active member of the series. Conclusion: All compounds showed better antibacterial, antifungal and cytotoxic activities, which may provide a ground to prepare enhanced molecules with much higher antibacterial activities.

Aims: This study aimed at synthesizing, analyzing, and utilizing two new direct dyes based on chromene derivatives as the chromophoric moiety in dyeing wool, silk, and cotton, with good color strength, light fastness, and other desirable features. Background: New direct dyes with antimicrobial activities for Gram-positive, Gram-negative bacteria, and fungus are being developed. These dyes are used on cotton, silk, and wool materials, which have excellent light fastness, washing, rubbing, and perspiration fastness. Methods: All dyeing fabrics were tested for antibacterial activity. As a part of the experiment, parent structure 1 was previously synthesized. Then, diazotization and coupling reactions were used to prepare these dyes. Results and Discussion: P-Aminobenzenesulfonic acid (C1) and 4-Aminoazobenzene-3,4'-disulfonic acid (C2) were diazotized in hydrochloric acid with sodium nitrite and then coupled with compound 1 in a molar ratio of 1:1 at 25 °C until the pH was fixed at 5. Finally, the monoazo and diazo direct dyes (D1 and D2) were prepared. Conclusion:Wool, silk, and cotton materials benefit from the increased antibacterial activities and dyeing qualities (exhaustion and fixing) of synthetic dyes. Furthermore, they offer excellent fastness qualities (light, rubbing, and perspiration).