An efficient asymmetric synthesis of (S)-atenolol: using hydrolytic kinetic resolution

Anti-Inflammatory, Antiallergic and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus costaricaensis

Amid the current COVID-19 pandemic, the emergence of several variants in a relatively high mutation rate (twice per month) strengthened the importance of finding out a chemical entity that can be potential for developing an effective medicine. In this study, we explored ethyl acetate (EtOAc) extract of a marine-derived fungus Aspergillus cosatricaensis afforded three butenolide derivatives, butyrolactones I, VI and V (1-3), two naphtho-γ-pyrones, TMC-256 A1 (4) and rubrofusarin B (5) and methyl p-hydroxyphenyl acetate (6). Structure identification was unambiguously determined based on exhaustive spectral analyses including 1D/2D NMR and mass spectrometry. The isolated compounds (1-6) were assessed for their in vitro anti-inflammatory, antiallergic, elastase inhibitory activities and in silico SARS-CoV-2 main protease (Mpro). Results exhibited that only butenolides (1 and 2) revealed potent activities similar to or more than reference drugs unlike butyrolactone V (3) suggesting them as plausible chemical entities for developing lead molecules.

Asperflaloids A and B from Aspergillus flavipes DZ-3, an Endophytic Fungus of Eucommia ulmoides Oliver

The fungus strain DZ-3 was isolated from twigs of the well-known medicinal plant Eucommia ulmoides Oliver and identified as Aspergillus flavipes. Two new alkaloids, named asperflaloids A and B (1 and 2), together with 10 known compounds (3-12) were obtained from the EtOAc extract of the strain. Interestingly, the alkaloids 1-4 with different frameworks are characterized by the presence of the same anthranilic acid residue. The structures were established by detailed analyses of the spectroscopic data. The absolute configuration of asperflaloids A and B was resolved by quantum chemistry calculation. All compounds were screened for their inhibitions against α-glucosidase and the antioxidant capacities. The results were that compound 3 had an IC50 value of 750.8 μM toward α-glucosidase, and the phenol compounds 7 and 8 exhibited potent antioxidant capacities with IC50 values 14.4 and 27.1 μM respectively.

Cobalt-Catalyzed 1,4-Aryl Migration/Desulfonylation Cascade: Synthesis of α-Aryl Amides

A cobalt-catalyzed 1,4-aryl migration/disulfonylation cascade applied to α-bromo N-sulfonyl amides was developed. The reaction was highly chemoselective, allowing the preparation of α-aryl amides possessing a variety of functional groups. The method was used as the key step to synthesize an alkaloid, (±)-deoxyeseroline. Mechanistic investigations suggest a radical process.

Cobalt-Catalyzed Cross-Coupling of α-Bromo Amides with Grignard Reagents

A cobalt-catalyzed cross-coupling between α-bromo amides and Grignard reagents is disclosed. The reaction is general and allows access to a large variety of α-aryl and β,γ-unsaturated amides. Some mechanistic investigations have been undertaken to determine the nature of the intermediate species.

Fast liquid chromatography for racemic atenolol acetate separation-The analytical protocol

Kinetic resolution of (R,S)-atenolol is a faster strategy to produce (S)-atenolol. Since this racemate is a less soluble compound, resolution of its ester offers high concentrations in the process. A good analytical method is required to observe the enantiomer concentrations. This paper described application of ultra-fast liquid chromatography on the atenolol ester separation using different resolution media and analytical procedures. Chiralcel OD column resolved the ester. The chromatograms indicated different characteristics of the process. The enantiomers could be recognized by the column in less than 1 (one) hour. Symmetrical peaks were obtained, but several procedures produced peaks with wide bases and slanted baselines. Efficient enantioresolution was obtained at high mobile phase flow rate, decreased concentration of amine-type modifier, but increased alcohol content in the mobile phase. High UV detection wavelength was required. At 1.0 mL/min, the (90/10/0.5) composition resulted α = 1.46 and R_S  = 0.9998 that were good separation.

Inositol Derivatives and Phenolic Compounds from the Roots of Taraxacum coreanum

In this study, the characterization of chemical constituents and biological activity of the roots of Taraxacum coreanum (Asteraceae) was attempted. Phytochemical investigation of the roots of T. coreanum led to the isolation of two new inositol derivatives, taraxinositols A (1) and B (2), and a new phenolic compound, taraxinol (16), together with twenty known compounds including four inositol derivatives, neo-inositol-1,4-bis (4-hydroxybenzeneacetate) (3), chiro-inositol-1,5-bis(4- hydroxybenzeneacetate) (4), chiro-inositol-2,3-bis (4-hydroxybenzeneacetate) (5) and chiro-inositol- 1,2,3-tris (4-hydroxybenzeneacetate) (6), nine phenolic compounds: p-hydroxybenzaldehyde (7), vanillin (8), syringaldehyde (9), vanillic acid (10), 4-methoxyphenylacetic acid (11), 4-hydroxy- phenylacetic acid methyl ester (12), optivanin (13), isoferulic acid (14) and dihydroconiferyl alcohol (15), four coumarins: nodakenetin (17), decursinol (18), prangol (19) and isobyakangelicin (20), and three lignans: syringaresinol-4′-O-β-d-glucoside (21), syringaresinol (22), and pinoresinol (23). The structures of isolated compounds were determined on the basis of spectroscopic analysis. Among the isolated compounds, vanillic acid, isoferulic acid and syringaresinol showed radical scavenging activity with IC₅₀ values ranging from 30.4 to 75.2 μM.

Enantio-conversion and -selectivity of racemic atenolol kinetic resolution using free Pseudomonas fluorescens lipase (Amano) conducted via transesterification reaction

Effects of reaction parameters on kinetic resolution of racemic atenolol usingPseudomonas fluorescenslipase were investigatedviatransesterification for production of pharmacologically active eutomer (S)-atenolol with high enantiomeric purity.

Anti-allergic Inflammatory Activities of Compounds of Amomi Fructus

Activity-guided isolation of compounds from the fruits of Amomum xanthioides resulted in the purification of fourteen phenolic compounds, 4-hydroxy-benzaldehyde (1), 3,4-dihydroxybenzaldehyde (2), 3,5-dimethoxy-4-methylbenzaldehyde (3), syringic aldehyde (4), benzoic acid (5), 3,4-dihydroxy benzoic acid (6), vanillic acid (7), 3-hydroxy-2-methoxybenzoic acid (8), o-vanillic acid (9), phenylacetic acid (10), tyrosol (11), pyrocatechol (12), 1,2,4,5-tetramethoxybenzene (13), and 3,3′,5,5′-tetramethoxybiphenyl-4,4′-diol (14). To evaluate the anti-allergic inflammatory activities of these compounds, we examined the inhibitory effects of the isolates (1-14) on histamine release and on the expressions of tumor necrosis factor (TNF)-α and interleukin (IL)–6 genes by using human mast cells. Of the tested compounds, 9, 11, and 13 suppressed histamine release from mast cells, and all isolates attenuated the expressions of the pro-inflammatory cytokines, TNF-α and IL-6 genes in human mast cells.

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

Following an optimized multicomponent procedure, an aryl amine, a ketone, and a cyclic ether or an alcohol molecule are assembled in a one-pot synthesis by nucleophilic radical addition of ketyl radicals to ketimines generated in situ. The reaction occurs under mild conditions by mediation of the TiCl4/Zn/t-BuOOH system, leading to the formation of quaternary β-amino-ethers and -alcohols. The new reaction conditions guarantee good selectivity by preventing the formation of secondary products. The secondary products are possibly derived from a competitive domino reaction, which involves further oxidation of the ketyl radicals.

Continuous and convergent access to vicinyl amino alcohols

A four module convergent chemical assembly system delivers two classes of vicinyl amino alcohol and five APIs.

Lipase-catalyzed green synthesis of enantiopure atenolol

A new green route is proposed for the synthesis of enantiopure atenolol (a β₁-blocker).

Chemical constituents from the fruits of Forsythia suspensa and their antimicrobial activity

Lignans and phenylethanoid glycosides purified from Forsythia suspensa were reported to display various bioactivities in the previous literature, including the antimicrobial activity. Therefore, the present research is aimed to purify and identify the chemical constituents of the methanol extracts of fruits of F. suspensa. The methanol extracts of fruits of F. suspensa were fractionated and further purified with the assistance of column chromatography to afford totally thirty-four compounds. Among these isolates, 3 β -acetoxy-20 α -hydroxyursan-28-oic acid (1) was reported from the natural sources for the first time. Some of the purified principles were subjected to the antimicrobial activity examinations against Escherichia coli to explore new natural lead compounds.

Cerebrosides and 2-pyridone alkaloids from the halotolerant fungus Penicillium chrysogenum grown in a hypersaline medium

Five new cerebrosides, chrysogesides A-E (1-5), and two new 2-pyridone alkaloids, chrysogedones A and B (6 and 7), were isolated from the fermentation broth of Penicillium chrysogenum PXP-55, a halotolerant fungus grown in a hypersaline medium. Among them, chrysogesides B-D (2-4) are the first cerebrosides that contain an unsaturated C(19)-fatty acid. Their structures were identified by spectroscopic and chemical methods, including CD spectroscopy as well as the modified Mosher's method. Compound 2 showed antimicrobial activity against Enterobacter aerogenes with an MIC value of 1.72 μM.

New domino radical synthesis of aminoalcohols promoted by TiCl4-Zn/t-BuOOH system: selective hydroxyalkylation of amines in alcohol or in cyclic ether cosolvents

We report a new and fast domino synthesis of aminoalcohols under mild conditions. The free-radical reaction of aliphatic and aromatic amines with alcohol cosolvents is promoted by means of the TiCl(4)-Zn/t-BuOOH system. According to the proposed mechanism, the amine reacts with two molecules of alcohol in an electrophilic-nucleophilic cascade process. This procedure, if compared with the TiCl(3)/t-BuOOH-mediated protocol previously reported, appears to be more selective, of more general applicability and affords the desired products in higher yields. Besides, with the same catalytic system it was possible to promote the reaction of primary arylamines with two molecules of cyclic ether, leading to the formation of a wider range of functionalized aminoalcohols.

Solvent-Free Microwave Synthesis of Aryloxypropanolamines by Ring Opening of Aryloxy Epoxides

The ring opening reaction of aryloxyepoxides with isopropylamine under solvent-free microwave irradiation produced therapeutically useful -blockers-aryloxypropanolamines in excellent yield (up to 98%) in 10 minutes which is considerably less than the time taken in classical heating ( hours).

Ruthenium-catalyzed selective monoamination of vicinal diols

The monoamination of vicinal diols in the presence of in situ generated ruthenium catalysts has been investigated. Among the various phosphines tested in combination with [Ru(3)(CO)(12)], N-phenyl-2-(dicyclohexyl-phosphanyl)pyrrole showed the best performance. After optimization of the reaction conditions this system was applied to different secondary amines and anilines as well as a number of vicinal diols. With the exception of ethylene glycol, monoamination of the vicinal diols occurred selectively and the corresponding amino alcohols were obtained in good yields, producing water as the only side product.