Gas‐phase fragmentation reactions of protonated benzofuran‐ and dihydrobenzofuran‐type neolignans investigated by accurate‐mass electrospray ionization tandem mass spectrometry

We have investigated gas‐phase fragmentation reactions of protonated benzofuran neolignans (BNs) and dihydrobenzofuran neolignans (DBNs) by accurate‐mass electrospray ionization tandem and multiple‐stage (MSⁿ) mass spectrometry combined with thermochemical data estimated by Computational Chemistry. Most of the protonated compounds fragment into product ions B ([M + H–MeOH]⁺), C ([ B –MeOH]⁺), D ([ C –CO]⁺), and E ([ D –CO]⁺) upon collision‐induced dissociation (CID). However, we identified a series of diagnostic ions and associated them with specific structural features. In the case of compounds displaying an acetoxy group at C‐4, product ion C produces diagnostic ions K ([ C –C₂H₂O]⁺), L ([ K –CO]⁺), and P ([ L –CO]⁺). Formation of product ions H ([ D –H₂O]⁺) and M ([ H –CO]⁺) is associated with the hydroxyl group at C‐3 and C‐3′, whereas product ions N ([ D –MeOH]⁺) and O ([ N –MeOH]⁺) indicate a methoxyl group at the same positions. Finally, product ions F ([ A –C₂H₂O]⁺), Q ([ A –C₃H₆O₂]⁺), I ([ A –C₆H₆O]⁺), and J ([ I –MeOH]⁺) for DBNs and product ion G ([ B –C₂H₂O]⁺) for BNs diagnose a saturated bond between C‐7′ and C‐8′. We used these structure‐fragmentation relationships in combination with deuterium exchange experiments, MSⁿ data, and Computational Chemistry to elucidate the gas‐phase fragmentation pathways of these compounds. These results could help to elucidate DBN and BN metabolites in in vivo and in vitro studies on the basis of electrospray ionization ESI‐CID‐MS/MS data only.     

Transition‐Metal‐Free Ring‐Opening Silylation of Indoles and Benzofurans with (Diphenyl‐tert‐butylsilyl)lithium

A practical method is presented for ring opening various indoles and benzofurans with concomitant stereoselective silylation using readily generated (diphenyl‐tert ‐butylsilyl)lithium to afford ortho ‐β‐silylvinylanilines or ‐phenols. Dearomatization of the heteroarene core proceeds in the absence of any transition‐metal catalyst through addition of a silyl anion and a subsequent stereoselective β‐elimination. DFT calculations provide insight into the mechanism. Functionalizing C−X bond cleavage of heteroarenes is rare and generally requires transition‐metal catalysts.     

Synthesis and biological evaluation of some novel thiadiazole-benzofuran hybrids as potential antitumor agents

Two series of novel 1,3,4-thiadiazole-benzofuran and 1,3,4-thiadiazole-furochromene derivatives were synthesized through heterocyclization of alkyl 2-(1-(6-hydroxy-4,7-dimethoxybenzofuran-5-yl)ethylidene)hydrazine-1-carbodithioate 3a–f and 2-(1-(5-methoxy-8-methyl-2,6-dioxo-2,6-dihydropyrano[3,2-g]chromen-3-yl)ethylidene)hydrazinecarbothioamide 9a,b with various hydrazonoyl halides, respectively. The structure of the newly synthesized products was elucidated through elemental analysis, spectral data and alternative routes whenever possible. Ten new compounds were evaluated for their anticancer activity against the human breast carcinoma (MCF-7) cell lines in comparison with reference doxorubicin using MTT assay. The results showed that some new compounds have promising anticancer activity.     

Efficient total synthesis of naturally occurring anti-TMV compound gramniphenol G

An efficient synthesis of Gramniphenol G identified as 2-(4′-Methoxyphenyl)-7,7-dimethyl-7H-furo[3,2-g]chromene and originally isolated from the plant Arundina gramnifolia belonging to orchidaceae family was accomplished starting from resorcinol. The key step involves the oxidative cyclization of o-vinyl phenol to provide benzofuran moiety.     

Benzoxocin, benzoxepin and benzofuran frameworks from 5-glyco-4-nitrocyclohex-1-enes through Nef reaction and intramolecular cyclization

By treatment of sodium nitronate salts of 5-glyco-4-nitrocyclohexenes with hydrochloric acid, five new bicyclic ethers with six-membered rings fused to five-, seven-, or eight-membered rings have been synthesized; also a mechanism for their formation is proposed. Structural elucidation of the new compounds is based on spectroscopic data, as well as on their comparison with those of closely related substances.     

Direct Dimesitylborylation of Benzofuran Derivatives by an Iridium-Catalyzed C−H Activation with Silyldimesitylborane

Direct dimesitylborylation of benzofuran derivatives by a C−H activation catalyzed by an iridium(I)/N-heterocyclic carbene (NHC) complex in the presence of Ph₂MeSi-BMes₂ afforded the corresponding dimesitylborylation products in good to high yield with excellent regioselectivity. This method provides a straightforward route to donor–(π-spacer)–acceptor systems with intriguing solvatochromic luminescence properties.     

Synthesis,Molecular Docking,and Biofilm Formation Inhibitory Activity of Bis(Indolyl)Pyridines Analogues of the Marine Alkaloid Nortopsentin

An efficient and simple protocol for the synthesis of a new class of diverse bis(indolyl)pyridines analogues of the marine alkaloid nortopsentin has been reported. A one-pot four-component condensation of 3-cyanocarbomethylindole, various aldehyde, 3-acetylindole, and ammonium acetate in glacial acetic acid led to the formation of 2,6-bis(1H-indol-3-yl)-4-(substituted-phenyl)pyridine-5-carbonitriles. Additionally, 2,6-bis(1H-indol-3-yl)-4-(benzofuran) pyridine-5-carbonitriles were prepared via a one-pot four-component condensation of 3-cyanocarbomethylindole, various N-substituted-indole-3-aldehydes, 2-acetylbenzofuran, and ammonium acetate. The synthesized compounds were evaluated for their ability to inhibit biofilm formation against the Gram-positive bacterial reference strains Staphylococcus aureus ATCC 6538 and the Gram-negative strain Escherichia coli ATCC 25922. Some of the new compounds showed a marked selectivity against the Gram-positive and Gram-negative strains. Remarkably, five compounds 4b, 7a, 7c, 7d and 8e demonstrated good antibiofilm formation against S. aureus and E. coli. On the other hand, the release of reducing sugars and proteins from the treated bacterial strains over the untreated strains was considered to explain the disruption effect of the selected compound on the contact cells of S. aureus and E. coli. Out of all studied compounds, the binding energies and binding mode of bis-indole derivatives 7c and 7d were theoretically the best thymidylate kinase, DNA gyrase B and DNA topoisomerase IV subunit B inhibitors.     

K2CO3促进苯并呋喃单元3-位与硫酚构建C-S键

本文在前期工作基础上进一步考察了2-位支链酮苯并呋喃单元在3位与硫酚构建C-S键的反应。研究发现,以K₂CO₃作碱,苯并呋喃单元2-位官能团为不同链长的脂肪酮时能高效地合成各种不同取代基的3-芳硫基苯并呋喃衍生物,所得产物经核磁共振、HRMS等方法进行了表征。该反应具有条件温和、底物适用范围广、操作简单、产率高、环境友好等优点,可为含有芳香烃硫基取代的天然产物及复杂药物分子的合成提供潜在的合成途径。     

Radical-induced expeditious stereoselective synthesis of 2-alkyl 3-allyl trans-2,3-dihydrobenzofurans (TADHBs)

A thorough study on radical-induced cyclopropyl ring fragmentation with encompassed olefinic and cyclopropane environment has been performed. Interestingly, the fragmentation has occasioned onto a stereoselective synthesis of 3-allyl trans-2,3-dihydrobenzofurans with impressive yields. The trans-dihydrobenzofurans are present as central core in many molecules of medicinal interest and the present protocol deliver a straight forward access to the embedded molecular architecture.     

Synthesis and Antimicrobial Activity of δ-Viniferin Analogues and Isosteres

The natural stilbenoid dehydro-δ-viniferin, containing a benzofuran core, has been recently identified as a promising antimicrobial agent. To define the structural elements relevant to its activity, we modified the styryl moiety, appended at C5 of the benzofuran ring. In this paper, we report the construction of stilbenoid-derived 2,3-diaryl-5-substituted benzofurans, which allowed us to prepare a focused collection of dehydro-δ-viniferin analogues. The antimicrobial activity of the synthesized compounds was evaluated against S. aureus ATCC29213. The simplified analogue 5,5′-(2-(4-hydroxyphenyl)benzofuran-3,5-diyl)bis(benzene-1,3-diol), obtained in three steps from 4-bromo-2-iodophenol (63% overall yield), emerged as a promising candidate for further investigation (MIC = 4 µg/mL).