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Data on the intramolecular Diels-Alder reaction in the 2-alkenylfuran series are generalised. The methods and conditions for the formation of tricyclic systems are considered. The effect of substituents in the furan and unsaturated fragments on the cycloaddition are discussed. The results of using this reaction for the synthesis of alkaloids and terpenoids are presented.

The tandem [4+2] cycloaddition between hexafluoro-2-butyne and bis-furyl dienes, like difurfuryl ester, at room temperature leads to the kinetically controlled "pincer"-adducts-annulated 4a,8a-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes. On the other hand, if these reactions proceed at 140 °C, only the thermodynamically controlled "domino"-adducts-annulated 2,3-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes-are formed. Therefore, a very rare and unexpected example of full kinetic and thermodynamic control in the Diels-Alder reaction is reported in this paper. © 2018 The Royal Society of Chemistry.

A rare example of chemospecificity in the tandem Diels-Alder reaction of activated alkynes and bis-dienes has been revealed. The reaction between bis-furyl dienes and DMAD occurs at 25-80 °C and leads to kinetically controlled "pincer" adducts, 4a,8a-disubstituted 1,4:5,8-diepoxynaphthalenes. On the contrary, only thermodynamically controlled "domino" adducts (2,3-disubstituted 1,4:5,8-diepoxynaphthalenes) are formed in the same reaction at 140 °C. The "pincer" adducts can be transformed to the "domino" adducts at heating. The rate constants for reactions of both types were calculated using dynamic 1H NMR spectroscopy. © 2018 American Chemical Society.

It has been proved that the reaction between furfuryl amines and N-R-maleimides leads to the formation of aza-Michael addition products-3-(furylmethylamino)-N-R-pyrrolidine-2,5-diones, instead of 7-oxa-2-azabicyclo[2.2.1]hept-5-enes, as this journal reported previously. © The Royal Society of Chemistry 2017.

The title compound, C15H19NO4, is the a product of the esterification of the corresponding carbonic acid with methanol. The molecule comprises a fused tetracyclic system containing three five-membered rings (2-pyrrolidinone, tetrahydrofuran and dihydrofuran) and one seven-membered ring (azepane). The five-membered rings have the usual envelope conformations, with the quaternary C atom being the flap atom for the 2-pyrrolidinone ring, and the ether O atom being the common flap atom for the remaining rings. The seven-membered azepane ring adopts a chair conformation with the methine and middle methylene C atoms lying above and below the mean plane defined by the remaining five atoms. The carboxylate substituent is rotated by 77.56(5)° with respect to the base plane of the tetrahydrofuran ring. In the crystal, the molecules are bound by weak C - H⋯O hydrogen-bonding interactions into puckered layers parallel to (001). © 2015.

Selective catalytic (10% Pd/C) hydrogenation of the double bond in the oxabicyclo[2.2.1]heptene fragment of substituted fused 1-oxo-3a,6-epoxyisoindoles is described. A continuous-flow hydrogenation device that incorporates in situ hydrogen generation by electrolysis of water was used. Changing the hydrogen source from water to deuterium oxide provides possibility to synthesize deuterated oxoepoxyisoindolones. Hydrogenation is stereoselective to give exclusively exo-cis deuterated derivatives. © 2015 Springer Science+Business Media, Inc.

The reaction of readily accessible (3-furyl)allylamines with maleic anhydride, followed by a domino sequence involving acylation/cycloaddition/proton shift steps, led to the formation of furo[2,3-f]isoindoles - the aza-analogs of pinguisane-type sesquiterpenes. The key intramolecular Diels-Alder vinylfuran (IMDAV) reaction proceeded under mild conditions, with high levels of diastereoselectivity and satisfactory yields. © 2015 Elsevier Ltd.

A method for the synthesis of hydrogenated furyl-, furylvinyl-, thienyl-, and pyrrolinyl-substituted quinazolin-4-ones was developed. A possibility of the reaction of 2-furylquinazolines with maleic anhydride was demonstrated. A number of quinazolines obtained were subjected to a primary bioscreening on inhibition of acetylcholinesterase. © 2015 Springer Science+Business Media New York.

The intramolecular Diels - Alder reaction of readily accessible 4-substituted 4-(N-furfuryl)aminobut-1-enes was studied and a new one-step method was developed for the synthesis of 6,8a-epoxy-1,2,3,4,4a,5,6,8a- octahydroisoquinoline (3-aza-11-oxatricyclo[6.2.1.0 1,6]undec-9-ene) derivatives. The [4+2]-cycloaddition proceeds stereoselectively to form exo-adducts. The influence of substituents at the nitrogen atom in 4-(N-furfuryl)aminobut-1-enes on the cycloaddition pathway was examined.

An acid-mediated intramolecular Friedel-Crafts intramolecular alkene alkylation of the ortho-alkyl group in the N-aryl-amino moiety of various N-(1-allylcycloalkyl)-N-arylamines resulting in alkyl-substituted 3′,4′-dihydro-1′H-spiro[cycloalkane-1,2′-quinolines] is described. The mechanistic details of this intramolecular Friedel-Crafts alkylation by an alkene moiety can be explained by an intramolecular alkylation with ipso substitution of alkyl groups and their 1,2-rearrangement. The scope and limitations of this reaction were determined. As a conclusive proof of the proposed mechanism, previously unknown interesting by-products, dispiro[quino[6,7-f]quinoline-3,1′:9,1″-bis(cycloalkanes), were isolated and characterized. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

The published data on the intramolecular Diels-Alder reaction in compounds of the 2-alkenylfuran series are generalised. The methods and conditions for the preparation of tricyclic systems are considered. The effects of the substituents in the furan and the unsaturated fragments on the cycloaddition are discussed. The application of this reaction to the synthesis of alkaloids and terpenoids is exemplified. The bibliography includes 168 references. © 2005 Russian Academy of Sciences and Turpion Ltd.

An unprecedented intramolecular Friedel-Crafts ipso-alkylation at the ortho-alkyl group of the N-arylamino moiety of 1-allyl-1-N- arylaminocycloalkanes to give alkyl substituted dihydrospiro[(1H) quinoline-2,1′-cycloalkanes] is reported. Unexpected results were explained in the context of intramolecular ipso-substitution of alkyl groups and their 1,2-rearrangement. A plausible mechanism for this type of Friedel-Crafts alkylation by an alkene moiety promoted by a Brönsted acid (H2SO4) is proposed. © 2004 Elsevier Ltd. All rights reserved.

The reactions of 3-acetyl-3-aza-11-oxatricyclo[6.2.1.0 1,6]undec-9-ene and its 9,10-epoxy derivative with bromine and Ac2O/BF3·OEt2 under different conditions were studied. Unusual products of Wagner-Meerwein rearrangement bearing the olefin fragment (5-aza-2-oxatricyclo[6.2.1.0 3,9]-undecen-3-enes) were isolated and characterized by X-ray analysis.

The straightforward synthesis of new isoindolo[2,1-a]quinoline derivatives from 2,4-disubstituted 1,2,3,4-tetrahydroquinolines bearing a furan fragment via the intramolecular Diels-Alder reaction is reported. The synthesis of key precursors was realized with excellent levels of diastereoselectivity either by Povarov reaction or by a multicomponent condensation approach. © Georg Thieme Verlag Stuttgart.

Acylation of 4-(furyl-2)-4-R-aminobut-1-enes and 4-R-4-furfurylaminobut-1- enes with maleic anhydride, acryloyl chloride or allylhalides provided 3-aza-10-oxatricyclo[5.2.1.01.5]decenes. The tricycles are formed via an initial amide formation followed by a stereoselective exo-IMDAF (Intramolecular Diels-Alder of Furan). In case of competing cycloaddition (for compounds possessing two furan or two dienophilic moieties) the most substituted fivemembered cycle is preferably annulated. Refluxing of 4-R-4- furfurylaminobut-1-enes in acetic anhydride led to exo-3-aza-11-oxatricyclo[6.2. 1.01.6]undecenes with the pseudoequatorial substituent R-4. Treatment of 3-aza-10-oxatricyclo[5.2.1.01.5]decenes with PPA at 90-110 °C promoted cyclic ether opening, aromatization and intramolecular cyclization reactions sequence to give the corresponding tetracyclic compounds - tetrahydroisoindolo[2,1-a]quinolines and tetrahydroisoindolo[2,1-b][2] benzazepines in good yields. Unusual products of ipso-substitution in aromatic ring were obtained on cyclization of N-p-R-substituted 2-allyl-4-oxo-3-aza-10- oxatricyclo[5.2.1.01.5]dec-8-enes.

A series of 1- and 3-halo-substituted isoindolo[2,1-a]quinolines were obtained by means of electrophilic cyclization of methallyl- and allyl-substituted isoindolo-7-carboxylic acids. The influence of halogen atoms on the stereochemistry of the formation of key intermediates, 3a,6-epoxyisoindoles, was studied. © Georg Thieme Verlag Stuttgart.

The interaction between 1-furyl-1,2,3,4-tetrahydroisoquinolines and unsaturated acids derivatives (acryloyl, methacryloyl, and crotonoyl chloride, maleic and citraconic anhydride) was studied. It was shown that the reaction proceeds via amide formation and subsequent intramolecular Diels-Alder reaction of the furan (IMDAF). The [4+2] cycloaddition proceeded under mild reaction conditions (25-80 °C) and afforded only the exo-adduct in a high yield. With this method, a new approach to the isoindolo[1,2-a]isoquinoline system, the basic structural element of alkaloids Jamtine, Hirsutine, and Nuevamine, is proposed. © 2009 Elsevier Ltd. All rights reserved.

The title compound, C26H28N2O 9·1.5H2O, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol-ecules occupying a special position on a twofold axis. The organic mol-ecule comprises a fused penta-cyclic system containing two five-membered rings (cyclopentane and tetrahydrofuran) and three six-membered rings (piperidinone, tetra-hydropyridine and benzene). The five-membered rings have the usual envelope conformations, and the central six-membered piperidinone and tetra-hydropyridine rings adopt boat and sofa conformations, respectively. In the crystal, there are three independent O-H⋯O hydrogen bonds, which link the organic mol-ecules and water mol-ecules into complex two-tier layers parallel to (001). The layers are further linked into a three-dimensional framework by attractive inter-molecular carbonyl-carbonyl inter-actions.

A new straightforward synthesis of 8,10a-epoxypyrido[2,1-a]isoindoles and their 7-carboxylic acids from 2,6-difurylsubstituted piperidin-4-ones and maleic anhydride or acryloyl chloride via the intramolecular Diels-Alder reaction has been demonstrated. It has been shown that a one-stage synthesis of the title compounds can be performed under mild conditions and with high levels of regio-and stereoselectivity from easily accessible 2-furylpiperidines. © Georg Thieme Verlag Stuttgart - New York.

Partly hydrogenated 2-[5-methyl(bromo, nitro)furan-2-yl]-substituted furo[3,2-c]quinolines, pyrano- [3,2-c]quinolines, and 4-ethoxyquinolines were synthesized by the imino Diels-Alder (Povarov) reaction. Cycloadditions of these compounds with maleic, citraconic, and dibromomaleic anhydrides, as well as with acryloyl, methacryloyl, and cinnamoyl chlorides led to the formation of substituted epoxyisoindolo[2,1-a]- quinolines and -quinolinecarboxylic acids. Oxidation of the double C=C bond in the adducts, esterification of the carboxy group, and aromatization of the 7-oxabicycloheptene fragment were accomplished. © Pleiades Publishing, Ltd., 2010.