Furan Framework Research Articles

Tailoring the naphtho-[2,3]-furan framework for Pb2+ ion sensing through substitutional effect

This article describes the synthesis of naphthofuran-based probes NF, NNF, and BNFvia a multiple-step synthetic approach and their characterization using standard spectroscopic techniques such as FT-IR, 1H NMR, 13CNMR and HR-MS spectrometry. The inclusion complex (ICNNF) has also been synthesized by encapsulating the NNF molecule into the hydrophobic cavity of β-CD. The chemosensing properties of all these probes have been investigated using UV-visible and fluorescence spectroscopy. However, all these probes could interact with metal ions, only NNF showed chemoselectivity towards Pb2+ detection. The limit of detection (LOD) and binding constant were calculated to be 1.47 µM and 7.38 ⅹ 1010 M−2 for NNF using the Stern-Volmer and Bensi-Hiderland plots, respectively. Further studies revealed that the –NO2 group and furan oxygen in NNF simultaneously interacted with the empty orbital of Pb2+ to produce the "turn-on" spectra.

5,6-Diphenyl-1,3,4,7-tetra-p-tolyl-1,3,3a,7a-tetrahydropentaleno[1,2-c]furan

The reaction of (Z)-5-phenyl-1,3-di-p-tolylpent-2-en-4-yn-1-ol (1) with trimethylsilyl chloride in dichloromethane at ambient temperature gave a dimeric ether compound 2 in 30% yield. Subsequently, heating 2 in toluene under refluxing temperature rendered the title compound quantitatively. The structure of this tricyclic-fused compound was characterized using NMR, mass spectroscopy, and X-ray crystallography. This unique linear tricyclic fused furan framework is reported for the first time.

Synthesis of Polysubstituted Furan Frameworks via [3 + 2] Annulation of N-Enoxyimides with Chelated Alkynes Initiated by Rh(III)-Catalyzed C–H Activation

A variety of 2,3,5-trisubstituted furans were synthesized by virtue of a Rh(III)-catalyzed vinylic C-H coupling of N-enoxyimides with propargyl alcohols or amines. In this protocol, N-enoxyimides served as a one-oxygen and two-carbon synthon and the -OH/-NHR moiety in the alkynes was found to be crucial for realizing the desired chemo-/regioselectivity. Detailed experimental mechanistic studies together with DFT calculations clarified the sequential C-H activation/regioselective alkyne insertion/simultaneous O-N bond cleavage and hydrogen transfer/intramolecular nucleophilic addition/aromatization reaction path, which involved a distinctive Rh(V) carbene species as the active intermediate.

HFIP-assisted Brønsted acid catalysed synthesis of furan derivatives

The furan framework is ubiquitous in naturally occurring compounds, and furan-containing structures are also key intermediates to many industrially important chemicals and materials. There have been reports of numerous methods to synthesise furans, however most of them use transition metal catalysts or Brønsted acid catalysts under harsh conditions. This work describes the development of a new non-metal Brønsted acid catalytic method for the synthesis of 2-aryl-3-carboxylate ester furans and 2,3-diaryl furans from ynone substrates. The method was shown to be efficient under very mild reaction conditions with up to 94% product yields.

A one-pot ring-closure and ring-opening sequence for the cascade synthesis of dihydrofurofurans and functionalized furans.

We have developed a simple novel ring-closure and ring-opening pathway using an organo-base system for the synthesis of highly substituted dihydrofurofuran and furan frameworks via a triethylamine-catalyzed one-pot three-component reaction. The protocol involved a Knoevenagel and Michael adduct via Paal-Knorr cyclization with aromatic/aliphatic glyoxal and 2-cyanoacetophenone under mild and heating conditions with excellent yields through a simple filtration method. The merits of this methodology, including the use of easily available feedstocks and an inexpensive catalyst, Gram-scale synthesis, wide functional group tolerance, an open-air reaction setup, and no need for workup and column-chromatography procedures, make the developed methodology a practical way to access dihydrofurofurans and functionalized furans.

Rhodium-Catalyzed Diastereoselective [3 + 2] Cycloaddition of Carbonyl Ylide: An Access to the Core Ring System of Cordigol and Lophirone H

This paper describes a new synthetic strategy for the construction of tricyclic chromeno/quinolino furan frameworks via creation of two new rings and three contiguous stereogenic centers with high diastereoselectivity through a rhodium-catalyzed intramolecular carbonyl ylide cycloaddition reaction for the first time. This protocol allows the synthesis of the core ring system of natural products such as cordigol and lophirone H.

Palladium‐Catalyzed Allenylation/6π‐Electrocyclization and 1,3‐Hydrogen Migration: an Access to Naphtho[1,2‐b]furans

A novel Pd‐catalyzed method for the synthesis of various naphtho[1,2‐b]furans from propargyl carboxylates bearing a furanyl group with organoborons is described. This cascade reaction involves Pd0‐catalyzed allenylation, 6π‐electrocyclization and 1,3‐H migration process. Control experiments suggested the base (Cs2CO3) play an essential role for the hydrogen migration. Wide substrate scope with easily accessible starting materials and good functional group tolerance indicate that this protocol may provide a general approach to construct naphtho[1,2‐b]furan frameworks which are important in natural product synthesis and medicinal chemistry.

Diastereoselective ABB' Three-Component Synthesis of Highly Functionalized Spirooxindoles Bearing Five Consecutive Asymmetric Carbons.

The synthesis of spirooxindoles bearing tetrahydro-4 H-cyclopenta[ b]furan framework was established starting from isatin-derived aldehydes and 2 equiv of 1,3-dicarbonyl compounds involving a piperidine-catalyzed ABB' three-component domino process. This reaction was highly diastereoselective affording a single diastereomer of spirooxindoles with five consecutive asymmetric carbons including spiro and tetrasubstituted carbon centers. In addition, this waste-free (-2H2O) reaction showed high atom economy and step economy by creating four new bonds, including three C-C bonds and one C-O bond, and two rings (one carbo- and one heterocyclic) in a single operation. The mechanism of this three-component domino process involved sequential Knoevenagel condensation-Michael addition-intramolecular oxa-Michael addition-intramolecular aldol reactions.

Accessing Polyoxygenated Dibenzofurans via the Union of Phenols and o-Benzoquinones: Rapid Syntheses of Metabolites Isolated from Ribes takare.

The construction of polyoxygenated dibenzo[b,d]furan frameworks from the union of substituted phenols/naphthols and o-benzoquinones via a Michael-oxidation-oxa-Michael cascade is reported. The power of this transformation is demonstrated in the generation of a library of highly substituted dibenzofurans, featuring specifically substituted molecules containing broad ranges of functionality. The utility of this method is showcased in the total syntheses of two dibenzofurans isolated from Ribes takare, assembling the carbon scaffold of both natural products in one operation.

Chemoenzymatic routes to enantiomerically enriched and polyoxygenated perhydro-3,5a-methanoindeno[4,5-c]furans related to the tashironin class of sesquiterpenes.

The alcohol 12, which is available in eight steps from the enzymatically derived cis-1,2-dihydrocatechol 8, engages in an intramolecular alkoxy radical-mediated remote functionalization reaction to form the tetrahydrofuran 13, thus establishing the perhydro-3,5a-methanoindeno[4,5-c]furan framework associated with the biologically active tashironins. Various manipulations of compound 13 and certain derivatives allow for the formation of compounds bearing strong structural resemblances to the title natural products.

The short way to chiral compounds with hexahydrofluoreno[9,1-bc]furan framework: Synthesis and cytotoxic activity

A simple and efficient method for synthesizing chiral heterocyclic compounds with the hexahydrofluoreno[9,1-bc]furan framework via interaction between trans-4-hydroxymethyl-2-carene and aromatic aldehydes containing methoxy and hydroxyl moieties in the presence of montmorillonite clay was found. One of the synthesized compounds exhibited a high cytotoxic activity against lymphoblastoid cell line MT-4 (CTD50 0.9μM), which was higher than that of the comparative drug Doxorubicin. Death of cancer cells in this case substantially occurs via induction of apoptosis.

Chemo-enzymatic synthesis of new resveratrol-related dimers containing the benzo[b]furan framework and evaluation of their radical scavenger activities

The chemo-enzymatic synthesis and the evaluation of radical scavenger performance of resveratrol-related dimers with antioxidative power have been investigated. The dimeric compounds, containing the benzo[b]furan framework, were prepared via an oxidative dimerization catalyzed by a laccase from Trametes versicolor, followed by a treatment with the organic oxidant DDQ. This methodology can be useful for the synthesis of various 2,3-diarylbenzo[b]furans derivates, a class of compound that exhibits a wide range of biological activities.

ChemInform Abstract: Combined Oxypalladation/C—H Functionalization: Palladium(II)‐Catalyzed Intramolecular Oxidative Oxyarylation of Hydroxyalkenes.

AbstractThe method allows a stereoselective access to a tricyclic furan framework which bears a broad spectrum of functionalities.

Combined oxypalladation/C-H functionalization: palladium(II)-catalyzed intramolecular oxidative oxyarylation of hydroxyalkenes.

Combined oxypalladation/C-H functionalization: palladium(II)-catalyzed intramolecular oxidative oxyarylation of hydroxyalkenes.

Asymmetric synthesis of Pachastrissamine (Jaspine B) and its diastereomers viaη3-allylpalladium intermediates

A short route for the synthesis of Pachastrissamine (Jaspine B), an anhydrosphingosine derivative, and all three of its diastereomers is presented. The route consists of only 9 steps from the commercially available Garner's aldehyde. The furan framework is formed via an η(3)-allylpalladium intermediate.

Enantioselective Synthesis of Furo[2,3‐b]furans, a Spongiane Diterpenoid Substructure.

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Enantioselective Synthesis of Furo[2,3-b]furans, a Spongiane Diterpenoid Substructure

[structure: see text] A short and enantioselective synthesis of cis-fused 5-oxofuro[2,3-b]furans, being found in many spongiane diterpenoid natural products, is reported starting from inexpensive methyl 2-furoate. Moreover, the acid-catalyzed rearrangement of the furo[2,3-b]furan framework A to B is observed for some derivatives, suggesting a simple connection between natural products differing in the absolute configuration of the 3a,6a ring junction.