Furan Nucleus Research Articles

ChemInform Abstract: Addition and Cycloaddition Reactions of Furo(3,2‐b)pyrroles and Their Benzo(b) Analogues: An NMR Study of Structure of Products.

AbstractReaction of the furopyrroles (I) with the alkynoates (II) or (VI) yields the products (III) or (VII) by initial cycloaddition at the furan nucleus.

Addition and cycloaddition reactions of furo[3,2-b]pyrroles and their benzo[b] analogues: An NMR study of structure of products

Reaction of furo[3,2-b]pyrroles and their benzo[b] analogues with dimethyl butynedioate and ethyl propyonate were investigated. The reaction course is influenced by substituents on the system. Products of [4 + 2] cycloaddition to the furan or pyrrole nucleus as well as products of Michael addition to the benzo[b]furo[3,2-b]pyrrole system have been found. The structure of the products has been proven by 1H NMR and 13C NMR spectroscopy.

Studies in the furan series. 23. Preparation of some new 5‐substituted furfurylallylarylamines. Influence of substituents on the intramolecular Diels‐Alder (IMDA) reaction

AbstractSeveral new N‐allyl‐N‐(5‐substituted)‐2‐furfuryl‐p)‐toluidines IIIa‐e with Cl, Br, I, NO2 or CH3O groups in position 5 of the furan nucleus were prepared by allylation of the corresponding secondary furfurylaryl‐amines. Both, electron withdrawing and releasing substituents enhanced the yield of intramolecular [4+2] cycloaddition.

Reaction of 3-hetero-1,5-dialdehydes with tert-butyl cyanoacetate

The reaction of thiodiglycolaldehyde and diglycolaldehyde with tert-butyl cyanoacetate yields derivatives of tetrahydrothiopyran and tetrahydropyran, respectively. Similar reactions of diglycolaldehyde derivatives having a furan nucleus at the α-position yield d- xylo (major) and l- arabino (minor) C-pyranosyl derivatives. Starting from α-( S)-methoxy-α′-( R)-hydroxymethyldiglycolaldehyde, d- gluco and d- manno glycosides were obtained, the relative proportions of which depended on the time of reaction. In addition to the 1:1 addition products, minor products corresponding to 1:2 (dialdehyde:active methylene compound) addition were isolated.

New type of addition to 5-substituted 4-arylidene-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorates. Preparation of 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes

4-Arilidene-5-(N,N-dimethyliminium)-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorate I undergoes a 1,4-addition reaction with organic bases under re-formation of the furan nucleus; this behaviour has been utilized in the preparation of new 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes II, III. The structure of the prepared compounds has been confirmed by 13C and 1H NMR spectra.

An efficient and general methodology for the synthesis of the hetes: synthesis of (±)-5-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-hete)

The facile synthesis of (±)S-HETE illustrates a general synthetic approach to the HETES in which the key step involves the oxidative ring opening of an appropriately substituted furan nucleus.

Metabolic Basis for the Pulmonary Clara Cell as a Target for Pulmonary Carcinogenesis

The furan compound, 4-ipomeanol, is activated in lung tissue by cytochrome P-450 dependent oxidation to a highly reactive, electrophilic product that binds covalently to tissue macromolecules. Although the reactive metabolite(s) of 4-ipomeanol have not yet been definitively identified, recent studies with 3-methylfuran have indicated that a highly reactive, unsaturated dialdehyde is formed from microsomal oxidation and ring-opening of the furan nucleus. Metabolic experiments with 4-ipomeanol in intact lungs, lung slices, lung cells, lung microsomes and purified lung cytochromes P-450, supported the conclusion that the Clara cell is an important locus of cytochrome P-450 monooxygenase activity in lung. In vivo, 4-ipomeanol was bound covalently and caused necrosis preferentially in the pulmonary Clara cells of laboratory animals. Similarly, N-nitrosamines require metabolic activation mediated by the cytochrome P-450 monooxygenase system in the host organism. A number of nitrosamines which are lung carcinogens in rats and hamsters have been shown to bind preferentially to bronchial and bronchiolar Clara cells in these species. Early pathological changes occurred specifically in Clara cells and lung tumors that developed under continuous nitrosamine treatment originated from such altered Clara cells. The well-differentiated counterparts of these tumors clearly retained their ability to bind the nitrosamine that had induced their formation. Thus, the studies on these two different classes of compounds together supported the view that metabolism may be a factor critical to the progenitor role of the Clara cell in chemically-induced bronchogenic lung cancer.

ChemInform Abstract: RECENT ADVANCES IN FURAN CHEMISTRY. PART II

Publisher Summary This chapter presents the syntheses of the furan ring from monosaccharides, hydrofurans, 1, 4-dicarbonyl compounds, Feist–Benary synthesis, epoxides and glycols, alkynes, cumulenes. 1,3-dicarbonyl compounds can be converted into furans by methods other than the classical Feist–Benary method, the essential feature of which is alkylation by a haloketone or similar species. Because reduction plus elimination reactions may convert butenolides into furans, any butenolide synthesis can be a basis for a furan synthesis. The protonation of furan leads to polymerization because the ring can open to polyfunctional products or the protonated species can act as an electrophile and attack another furan molecule. Protons are easily detached from the furan nucleus, especially when some activating group is present. Even the carbonate ion catalyzes the deuteration of position 5 in 2-furoic acid salt. The reactions of furan with metals including lithium and potassium, copper, tin, mercury; and nonmetals including boron, silicon, phosphorus, and iodine are presented. The oxidation and reduction reactions of furan are also presented in the chapter.

Direct cyanation of the furan nucleus by chlorosulphonyl isocyanate

A series of furans are converted directly,by reaction with chlorosulphonyl isocyanate, into furancarbonitriles. A route to furfuralcarbonitriles is described involving a new application of the ruthenium dioxide - sodium metaperiodate oxidizing system.

ChemInform Abstract: SYNTHESIS AND PHARMACOLOGICAL ACTIVITY OF SOME 2,5‐DIALKOXY‐2‐(DIALKOXYMETHYL)TETRAHYDROFURANS

AbstractDie Furan‐acetale (I) liefern mit Ammoniumbromid/Alkohol/ Elektrolyse und Alkoholat die Diether (II), die auch durch Reaktion der Acetale (I) mti Alkohol/Brom erhalten werden.

Synthesis and pharmacological activity of some 2, 5-dialkoxy-2-(dialkoxymethyl)tetrahydrofurans

It is known [5] that 2~5-dimethoxy-2-dimethoxymethyl-2,5-dihydrofuran (IIla) is formed on electrolytic methoxylation of furfural dimethylacetal. We have established that the formation of acetal (IIIa) also occurs on carrying out the electrolysis with the more readily available furfural dioxalan (Ia) (method i). In this case reacetalization of the dioxalan group occurs together with electrolytic methoxylation of the furan nucleus. Reacetalization also takes place on alkoxylating dioxalan (Ia) by the action on its alcoholic solution of an alcoholic solution of bromine with the formation of the corresponding acetals (IIIa) or (IIIb) (method 2).

The preparation of some 1‐(2‐furyl)‐2‐arylethylenes

AbstractSome 1‐(2‐furyl)‐2‐arylethylenes, where the furan nucleus is substituted in position 5 with a methyl or p‐chlorophenyl group and where the aryl group is phenyl, p‐nitrophenyl, α‐naphthyl or β‐naphthyl, have been prepared by the Perkin reaction and subsequent decarboxylation of the acid. The compounds 1‐12 were prepared lor of photochemistry and photoelectron spectroscopy studies. Their geometrical configurations has been established by 1H nmr and ir spectra.

Transmission of polar effects arcoss the CH=CH link in styrylfuran system

Transmission of polar substituent effect through the vinylidene grouping in 5-(4-X-styryl)-2-furaldehydes (X = H, Cl, Br, COOCH3, CN and NO2) was studied by polarographic reduction of the aldehyde group as well as by kinetics of their condensation with malononitrile. The obtained transmission coefficients π' were compared with the corresponding values for systems, containing other links between the benzene and furan nuclei. Thermodynamic parameters of the condensation with malononitrile were determined. The transmission of polar effects is discussed also from the point of view of 1H NMR spectra.

The Intramolecular Diels-Alder Furan Approach in Synthesis : 11-oxatricyclo|6.2.1.01,6|undec-9-en-5-one

Abstract Although the synthetic potential of the intramolecular variant of the Diels-Alder reaction has now been fully recognized3, little attention has so far been paid to this type of addition using the furan nucleus as the diene partner4–8. The presence of an oxygenated cyclohexene system in several complex natural products (e.g. gibberellic acid, morphine), the diverse possibilities of the substituted 7-oxabicyclo |2.2.1|-2-heptene system for further transformation9, the expected enhanced reactivity and stereoselectivity of the intramolecular cycloaddition and the availability of a wide variety of commercial furan derivatives make the sequence a → b → c particularly attractive in total synthesis.

Polyesters Derived from Furan and Tetrahydrofuran Nuclei

Polyesters Derived from Furan and Tetrahydrofuran Nuclei

ChemInform Abstract: A COMPARISON OF THE ANTISEROTONIN, ANTIHISTAMINE, AND ANTICHOLINERGIC ACTIVITY OF CYPROHEPTADINE WITH ANALOGS HAVING FURAN NUCLEI FUSED TO THE 10,11‐VINYLENE BRIDGE

AbstractDie Kondensation der beiden Furane (IIa) und (IIb) mit 10‐Brom‐cyproheptadin (I) liefert die Addukte (IIIa) und (IIIb), die mit Tetraphenylcyclopentadienon (IV) zu (Va) und (Vb) gemäß einer Retro‐Diels‐Alder‐Reaktion reagieren.

Mass spectrometry of three furanic compounds containing two or three furan nuclei

Mass spectrometry of three furanic compounds containing two or three furan nuclei

On the reaction of trichloroacetyl isocyanate (TAI) with furan and pyrrole nucleus. A cautionary note on the application of the TAI-method to the classification of alcohols by PMR spectroscopy

On the reaction of trichloroacetyl isocyanate (TAI) with furan and pyrrole nucleus. A cautionary note on the application of the TAI-method to the classification of alcohols by PMR spectroscopy

The boron trifluoride-catalysed reaction of furan derivatives with ethane-1,2-dithiol

Treatment of furan, 3-isopropylfuran, benzofuran, and the diterpene 3-ketomarrubiin with ethane-1,2-dithiol in the presence of boron trifluoride–ether complex gives 2,5-(or 2,3-)dihydro-2-(2-mercaptoethylthio)furan derivatives. Similar treatment of furfuryl alcohol gives the corresponding 2-mercaptoethyl thioether, and furfural gives the corresponding thioacetal, but ethyl 2-furoate and 2-nitrofuran remain unaltered. The addition reaction is considered to occur through nucleophilic attack of a thiol group on the 2-position of a boron trifluoride-co-ordinated furan nucleus.

Experiments in the furan series. XIII. Interaction of substituents on the furan nucleus caused by electron impact

Experiments in the furan series. XIII. Interaction of substituents on the furan nucleus caused by electron impact