Base-Mediated Annulation of ortho-Iminophenols and ortho-Vinylphenols with MBH Carbonates of Isatins: Straightforward Access to Dihydrobenzofuran and Benzofuran Derivatives

We have developed a convenient synthetic protocol for efficient construction of significant dihydrobenzofuran and benzofuran scaffolds by Lewis base-mediated annulation reaction ortho-iminophenols and ortho-vinylphenols with MBH carbonates of isatins under mild and metal-free conditions. The selective generation of different kinds of dihydrobenzofuran and benzofuran derivatives was successfully achieved by employing different substituted isatin-derived MBH carbonates with ortho-N-tosyliminophenols and ortho-vinylphenols. The features included broad substrate scopes, excellent functional group compatibility, high molecular diversity, and atomic economy.

An Access to Highly Functionalized Dihydrobenzofuran Spirooxindole Scaffolds

We have developed an efficient protocol for the construction of polycyclic dihydrobenzofuran spirooxindole scaffolds via base promoted cascade annulation of Morita-Baylis-Hillman (MBH) carbonates of isatins with ortho-hydroxychalcones or ortho-hydroxy-β-nitrostyrenes. The complex polycyclic compounds were conveniently synthesized in satisfactory yields and with high diastereoselectivity. This protocol provides a swift and convenient approach for the assembly of diverse highly functionalized dihydrobenzofuran spirooxindoles and also features broad substrate scope, high molecular convergence, and excellent atomic economy.

gem-Difluorovinylation of alkynyl bromoarenes via dual nickel-/palladium-catalyzed cross-electrophile coupling

A dual nickel-/palladium-catalyzed gem-difluorovinylation of alkynyl bromoarenes is presented. This method proceeds smoothly to afford various dihydrobenzofuran compounds containing gem-difluorovinyl fragments with excellent stereoselectivities.

Organocatalytic enantioselective synthesis of dihydronaphthofurans and dihydrobenzofurans: reaction development and insights into stereoselectivity

Squaramide/cinchona alkaloid-derived bifunctional organocatalysts are in high demand in asymmetric transformations.

Asymmetric synthesis of functionalized 2,3-dihydrobenzofurans using salicyl N-phosphonyl imines facilitated by group-assisted purification (GAP) chemistry

In this work, we present a strategy for the preparation of functionalized 2,3-dihydrobenzofuran derivatives via the Cs₂CO₃-catalyzed domino annulation of enantiopure chiral salicyl N-phosphonyl imines with bromo malonates, which offers an avenue for the construction of 2,3-dihydrobenzofurans. Nineteen examples were synthesized in impressive chemical yields and diastereoselectivity. The products were purified simply by washing the crude mixtures with hexanes following group-assisted purification chemistry/technology to bypass traditional separation methods which often result in a loss of product. The absolute configuration was unambiguously assigned by X-ray structural analysis.

Chemical constituents from the stems of Acanthopanax senticosus with their inhibitory activity on α-glucosidase

A new aurone named (2Z)-2-[(4'-hydroxy-3'-methoxyphenyl) methylene]-6-methoxy-7-prenyl-3(2H)-benzofurane (1), together with five known compounds (2-6), were isolated from EtOAc-soluble extract of the stems of Acanthopanax senticosus. The chemical structures were elucidated on the basis of spectroscopic analyses. All isolates were evaluated for in vitro inhibitory activity on α-glucosidase. Among them, compounds 1 and 4 were found to exhibit moderate inhibitory activity on α-glucosidase with IC₅₀ value of 64.1 ± 1.2 and 48.9 ± 1.1 μM, respectively.[Formula: see text].

Tulipiferamide A, an Alkamide from Liriodendron tulipifera, Exhibits an Anti-Inflammatory Effect via Targeting IKKβ Phosphorylation

Three new alkamides, tulipiferamides A-C (1-3, respectively), and 30 known compounds (4-33) were obtained from the roots of Liriodendron tulipifera (Magnoliaceae). Dehydrotemisin (4), an elemane sesquiterpene lactone, was isolated for the first time from nature. The structures were deduced by the interpretation of NMR spectroscopic and MS spectral data. The geometries of the double bonds in tulipiferamides A-C (1-3, respectively) were determined on the basis of ¹H-¹H coupling constants and ¹³C chemical shifts. The presence of the alkamide type in this plant is reported for the first time. An analysis of the inflammatory response revealed that seven compounds (1, 4, 7, 9, 14, 23, and 27) suppressed the nitric oxide production induced by LPS in RAW264.7 macrophages. Furthermore, tulipiferamide A (1) inhibits NF-κB activation by selectively targeting IKKβ, an upstream kinase of NF-κB, resulting in the suppression of inflammatory mediators, including iNOS, COX-2, IL-1β, TNFα, and IL-6. Our results provide a rationale for the further development of tulipiferamide A as a selective IKKβ inhibitor to modulate inflammatory diseases.

Facile one-pot synthesis of ketones from primary alcohols under mild conditions

One-pot transformation of primary alcohols to ketones was achieved by using dibromoisocyanuric acid and Fe₂O₃. This synthetic method provides a variety of ketones in high yield under mild reaction conditions.

Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

γ-valerolactone (GVL)/H₂O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H₂O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δ_C/δ_H 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δ_C/δ_H 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

Virtual Screening, Docking, Synthesis and Bioactivity Evaluation of Thiazolidinediones as Potential PPARγ Partial Agonists for Preparation of Antidiabetic Agents

Background:

Peroxisome proliferator-activated receptor gamma (PPARγ) is one of the key targets of insulin resistance research, in addition to being ligand-activated transcription factors of the nuclear hormone receptor superfamily with a leading role in adiposeness activation and insulin sensitivity. They regulate cholesterol and carbohydrate metabolism through direct actions on gene expression. Despite their therapeutic importance, there are dose limiting side effects associated with PPARγ drug treatments, thus a new generation of safer PPARγ drugs are being actively sought after treatment.

Methods:

In this study, we used computer aided drug design to screen new series of PPARγ ligands, and synthesized a series of potential thiazolidinedione derivatives such as 5,7- dibenzyloxybenzyl-3-hydroxymethyl-4H-coumarin-4-ketone, using 4-steps to synthesize the target compounds and built streptozotocin (STZ) induced insulin resistance rat model to measure their antidiabetic activity.

Results:

We found that 10 mg/kg concentration of compound 0701C could significantly decrease blood glucose and serum PPARγ, serum insulin levels in insulin resistance model rat.

Conclusion:

We would conclude that compound 0701C might serve as a potential PPARγ partial agonist.

Synthesis of trans-disubstituted-2,3-dihydrobenzofurans by a formal [4 + 1] annulation between para-quinone methides and sulfonium salts

An efficient protocol for the synthesis of trans-disubstituted-2,3-dihydrobenzofurans through [4 + 1] annulation of para-quinone methides with sulfonium salts has been developed.

Diastereo- and enantioselective construction of an indole-based 2,3-dihydrobenzofuran scaffold via catalytic asymmetric [3+2] cyclizations of quinone monoimides with 3-vinylindoles

The first catalytic asymmetric [3+2] cyclization of quinone monoimides with 3-vinylindoles has been established, which constructed a biologically important 2,3-dihydrobenzofuran framework in high stereoselectivities (up to >95 : 5 dr, 96 : 4 er).

In vitro activity-guided identification of antioxidants in aged garlic extract

Activity-guided fractionation was applied on an aged garlic extract (AGE), reported to show strong antioxidant activity, in order to locate the key in vitro antioxidant ingredients by means of the hydrogen peroxide scavenging (HPS) assay as well as the ORAC assay. Besides the previously reported four tetrahydro-β-carbolines, (1R,3S)- and (1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid and (1R,3S)- and (1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-1,3-dicarboxylic acid, LC-MS/MS, LC-TOF-MS, and 1D/2D-NMR experiments led to the identification of coniferyl alcohol and its dilignols (-)-(2R,3S)-dihydrodehydrodiconiferyl alcohol, (+)-(2S,3R)-dehydrodiconiferyl alcohol, erythro-guaiacylglycerol-β-O-4'-coniferyl ether, and threo-guaiacylglycerol-β-O-4'-coniferyl ether as the major antioxidants in AGE. The purified individual compounds showed high antioxidant activity, with EC50 values of 9.7-11.8 μM (HPS assay) and 2.60-3.65 μmol TE/μmol (ORAC assay), respectively.

Strategies for the Synthesis of 2,3-Dihydrobenzofurans

This article gives an overview of synthetic approaches to the 2,3-dihydrobenzofuran ring system with an emphasis on recently developed methods. The synthetic approaches are classified according to the key bond(s) formed during the construction of the dihydrobenzofuran skeleton, and approaches of relevance to the synthesis of natural products are highlighted.

Maple syrup phytochemicals include lignans, coumarins, a stilbene, and other previously unreported antioxidant phenolic compounds

Twenty-three phenolic compounds were isolated from a butanol extract of Canadian maple syrup (MS-BuOH) using chromatographic methods. The compounds were identified from their nuclear magnetic resonance and mass spectral data as 7 lignans [lyoniresinol (1), secoisolariciresinol (2), dehydroconiferyl alcohol (3), 5'-methoxy-dehydroconiferyl alcohol (4), erythro-guaiacylglycerol-β-O-4'-coniferyl alcohol (5), erythro-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol (6), and [3-[4-[(6-deoxy-α-l-mannopyranosyl)oxy]-3-methoxyphenyl]methyl]-5-(3,4-dimethoxyphenyl)dihydro-3-hydroxy-4-(hydroxymethyl)-2(3H)-furanone (7)], 2 coumarins [scopoletin (8) and fraxetin (9)], a stilbene [(E)-3,3'-dimethoxy-4,4'-dihydroxystilbene (10)], and 13 phenolic derivatives [2-hydroxy-3',4'-dihydroxyacetophenone (11), 1-(2,3,4-trihydroxy-5-methylphenyl)ethanone (12), 2,4,5-trihydroxyacetophenone (13), catechaldehyde (14), vanillin (15), syringaldehyde (16), gallic acid (17), trimethyl gallic acid methyl ester (18), syringic acid (19), syringenin (20), (E)-coniferol (21), C-veratroylglycol (22), and catechol (23)]. The antioxidant activities of MS-BuOH (IC50>1000 μg/mL), pure compounds, vitamin C (IC50=58 μM), and a synthetic commercial antioxidant, butylated hydroxytoluene (IC50=2651 μM), were evaluated in the diphenylpicrylhydrazyl (DPPH) radical scavenging assay. Among the isolates, the phenolic derivatives and coumarins showed superior antioxidant activity (IC50<100 μM) compared to the lignans and stilbene (IC50>100 μM). Also, this is the first report of 16 of these 23 phenolics, that is, compounds 1, 2, 4-14, 18, 20, and 22, in maple syrup.