Current Organic Chemistry - Volume 27, Issue 15, 2023

γ-lactams, bearing one or more chiral centers are important scaffolds and widely occur in many natural and synthetic products of clinical interest, but the synthetic approaches mainly focus on the preparation of rings that display trisubstituted carbons, whereas only a few examples concern the construction of chiral γ- lactams that display tetrasubstituted carbon atoms. However, in recent years, the broad potential of these latter compounds was recognized and deserved high interest, owing to their complex three-dimensional features and structural rigidity. Thus, several efforts were engaged in the pursuit of new synthetic strategies towards γ-lactam rings that contain tetrasubstituted carbons that pose a particular challenge, and the present review gathers advances reported since 2015 about the enantioselective preparation of these molecules, carried out to exploit both internal and external asymmetric induction.

Tuberculosis (TB) is the major cause of mortality around the world and one of the most common diseases linked to AIDS. Due to the emergence of multi-drug resistance, extensive drug resistance, and total drug resistance strains, TB has become a difficult disease to treat. Isoxazole scaffold shows a wide range of biological activities, including anticancer, antibacterial, anti-tubercular, antiviral, and anti-inflammatory activities etc. Several isoxazole derivatives have been produced and few of them have shown comparable anti-tubercular activity with standard drugs. In this review, we have focused on reported isoxazole derivatives having anti-tubercular activity and summarized their structure-activity relationship.

Tetrazoles are important heterocycles in diverse branches of chemistry. Among the 5-substituted tetrazoles, the 5-amino derivatives are the most important by far as they show high chemical versatility and relevant applications in material chemistry, catalysis, agrochemistry, etc. Particularly in medicinal chemistry, they present a wide range of pharmacological properties. In the present review, we focus on the synthesis of 5- aminotetrazol from the desulfurization processes of thioureas using metal salts, hypervalent iodine compounds and halogenated reagents.

Nature-derived thiols such as cysteine, homocysteine, and reduced glutathione play diverse and important roles in both plant and animal cells. In plants, they maintain redox homeostasis and affect photosynthesis and signal transduction processes. In animals, changes in the levels of biothiols have been linked to cardiovascular disease, Alzheimer's disease, neuropsychiatric disorders, or stroke. The detection of biothiols in biological samples is, therefore, very important. For this purpose, rapid, sensitive, and non-invasive methods for their sensing in living cells are highly desirable.This perspective reviews the past five years of advances in coumarin fluorescent probes for biothiol detection. The design of the probes, the mechanisms of thiol detection, and the applications in live cell imaging are presented. The classification of probes based on the coumarin backbone was made on the basis of the mode of their interactions with the analyte.

Ring contraction reaction is among the several vital strategies in organic synthesis that can provide very diversified and useful molecular architecture. Among these strategies, the oxidative ring contraction is of special interest as it can give a more straightforward way of designing and synthesizing several complex natural products, specifically the oxindole alkaloids and some newer oxindole analogs. Even this methodology can be expanded to prepare dispiro-bisoxindoles-type compounds besides the dipolar cycloaddition methodology. In this review, we have tried to collect the reports on oxidative ring contraction reactions using several oxidants, like tert-Butyl hypochlorite, oxaziridine, dimethyldioxirane, N-bromosuccinimide, etc., in different reaction conditions for the synthesis of spiro-oxindole natural products as well as newer synthetic analogs.

Ruthenium-catalyzed olefin metathesis reactions were conducted in water with thermoresponsive block copolymers forming micelles. The block copolymers were prepared by living radical polymerization and consisted of a thermo-responsive and hydrophilic segments. The former segment included poly(N-isopropylacrylamide) or poly(N,N-diethylacrylamide), and the latter poly(sodium 4-styrene sulfonate), poly(sodium 2-acrylamido-2-methylpropanesulfonate) or poly(ethylene glycol). Homometathesis, cross-metathesis and ring-closing metathesis reactions proceeded to afford the products in moderate to good yields. Extraction efficiency from the reaction mixture was also studied.

Synthesis of a homologous series of 1-O-acyl xylose esters with long and very long acyl chains derived from fatty acids was performed via enzymatic esterification in one step using Candida antarctica lipase B. The effect of fatty acid chain length on the activity of the lipase was evaluated. Subsequently, the surface properties of the obtained products have been determined such as hydrophilic-lipophilic balance, critical micellar concentration, and surfactant packing parameter. Foaming and emulsifying ability were also measured. The highest conversion was obtained by using docosanoic acid as an acylant agent (67.50%). The surface tension values are between 25 mN.m^-1 for 1-O-octadecanoyl-D-xylopyranose and 47,17 mN.m^-1 for 1-O-docosanoyl-D-xylopyranose. The emulsifying abilities of all esters exceeded 80%. It was found that the surface properties of the surfactants are greatly affected by the fatty acid chain length. The surface parameters results revealed that the prepared compounds have a good surface activity. Additionally, these bio-surfactants display good emulsifying ability.

This report presents the synthesis of three innovative N-substituted 6α- piperazinomethyl-Δ⁴-3,17-diketo-steroids via the region-directed three-component condensation method. The compounds were produced from N-substituted piperazine derivatives and androst-4-en-3,17-dione (AD). Comprehensive physicochemical methods of analysis were employed to characterize the synthesized products. The study involved antibacterial testing of the synthesized compounds against Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, and Staphylococcus aureus 209P FDA, with a comparison to the amoxicillin/clavulanic acid composition. It further assessed antifungal activity against Aspergillus niger INA 00760, with results compared to amphotericin B and nystatin. Initial assessment of the antibacterial and antifungal activities exhibited by the synthesized compounds suggests that this series of N-substituted 6α-piperazinomethyl-Δ⁴-3,17-diketo-steroids holds great potential for further biological investigation.

In previous studies on bioactivities, some extracts from Glinus oppositifolius possessed antimicrobial, antifungal, antiplasmodial, anti-inflammatory, anti-diarrhoeic, antihyperlipidemic, and hepatoprotective. However, information on the xanthine oxidase inhibitors' properties of G. oppositifolius is still limited. For the purpose of discovering new leads with potential α-glucosidase inhibition, the less explored plant G. oppositifolius has been investigated. A new apigenin flavone glucoside, named apigenin-5-O-β-D-glucopyranosyl-8-C-β-Dglucopyranoside (7), together with seven known compounds (spergulacin (1), glinoside C (2), spergulacin A (3), spergulin B (4), spergulin A (5), vitexin (6), vicenin 2 (8)) were identified from Glinus oppositifolius (L.) Aug. DC. aerial parts. The identification of their structures involved a comprehensive analysis utilizing extensive 1D and 2D NMR techniques, mass spectrometry, and in comparison with those from references. Compound 7 (IC50 =257.90 ± 1.00 μM) showed better inhibition of α- glucosidase than acarbose (IC50 = 1021.47 ± 10.79 μM). Compound 8 (IC50 = 56.82 ± 1.95 μM) indicated a good XO inhibitory effect.