Synthesis of 2-imino-4-vinyl-2,5-dihydrofuran-3-carboxamides and some their chemical transformations

2-Imino-2,5-dihydrofuran-3-carboxamides containing 2-phenyl- and 2-furylvinyl substituents in position 4 of the furan ring were synthesized by condensation of 2-imino-4-methyl-2,5-dihydrofuran-3-carboxamides with the corresponding aldehydes. Acid hydrolysis of 4-(2-arylvinyl)-2-imino-2,5-dihydrofuran-3-carboxamides gave 4-(2-arylvinyl)-2-oxo-2,5-dihydrofuran-3-carboxamides, and their condensation with malononitrile resulted in the formation of 2-dicyanomethylidene derivatives.     

A concise synthesis of highly functionalized α,β-unsaturated γ-butyrolactones through ring contraction of 2H-pyran-2-ones

2-Oxo-5-(1-arylvinyl)-4-piperidin-1-yl-2,5-dihydrofuran-3-carbonitriles 3 have been synthesized through ring contraction of suitably functionalized 2H -pyran-2-ones 1 by a carbanion generated in situ from nitromethane 2 in good yield. In some cases their counterpart tautomers 2-oxo-5-(1-arylethylidene)-4-piperidin-1-yl-2,5-dihydrofuran-3-carbonitriles 4 have also been isolated and characterized as minor products.     

Synthesis of New Derivatives of 2-Imino-2,5-dihydrofuran-3-carboxamides,Containing Aromatic Substituents

Russian Journal of Organic Chemistry - Novel derivatives of 2-imino-2,5-dihydrofuran-3-carboxamides containing aromatic substituents in positions 2 and 4 of the iminodihydrofuran ring were...     

Reaction of alkyl 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylates with zinc enolates prepared from zinc and 1-arul-2-bromo-2-phenylethanones, 2 bromoindanone, and 2-bromo-6-methyltetralone

Alkyl 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylates react with zinc enolates prepared from 1-aryl-2-bromo-2-phenylethanones, 2-bromo indanone, 2-bromo-6-methyltetralone and zinc with formation of ethyl 4-(2-aryl-2-oxo-1-phenyl-ethyl)-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylates, alkyl 5,5-dimethyl-2-oxo-4-(1-oxoindan-2-yl)tetrahydrofuran-3-carboxylates, and ethyl 5,5-dimethyl-4-(6-methyl-1-oxo-1,2,3,4-tetrahydronaphthalen-2-yl)-2-oxotetrahydrofuran-3-carboxylates respectively, mainly as single diastereomers.     

Synthesis of New Polyconjugated Systems Containing Iminodihydrofuran and Benzene Rings

Russian Journal of Organic Chemistry - New polyconjugated systems containing iminodihydrofuran and benzene rings were successfully synthesized by reaction of 2-imino-2,5-dihydrofuran-3-carboxamide...     

Synthesis of Alkyl 4-(1-Alkyl-2-aryl-2-oxoethyl)-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylates

Zinc enolates derived from 1-aryl-2-bromoalkanones react with alkyl 5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylates to give alkyl 4-(1-alkyl-2-aryl-2-oxoethyl)-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylates. Reactions of the latter with amines, such as p-toluidine, cyclohexylamine, and piperidine, lead to the corresponding carboxamides.     

Cyanoacetylene and Its Derivatives: XXVI. Hydrohalogenation of 4-Alkyl-4-hydroxy-2-alkynenitriles

The reaction of 4-alkyl-4-hydroxy-2-alkynenitriles with hydrogen halides (HCl and HI) in dioxane is accompanied by intramolecular cyclization with formation of 5,5-dialkyl-4-halo-2-imino-2,5-dihydrofuran hydrohalides. Treatment of the latter with K₂CO₃ in ethanol yields 5,5-dialkyl-4-halo-2-imino-2,5-dihydrofurans.     

Synthesis and Structure of 5,5-Disubstituted N-[4-Methyl-3-phenylfuran-2(5H)-ylidene]-N′-phenylthioureas

Russian Journal of Organic Chemistry - The reaction of 5,5-disubstituted 4-methyl-3-phenyl-2,5-dihydrofuran-2-imines with phenyl isothiocyanate afforded...     

Reaction of 2-Imino-2,5-dihydrofuran-3-carboxamides with Benzaldehyde

Russian Journal of Organic Chemistry - The reaction of 2-imino-2,5-dihydrofuran-3-carboxamides with benzaldehyde in pentan-1-ol in the presence of piperidine gave new dihydrofuran derivatives with...     

Synthesis of Novel 2-(N-Substituted)imino-2,5-dihydrofuran-3-carboxamides Containing a Thiourea Residue and an Oxothiazolidinylidene Ring

Russian Journal of Organic Chemistry - Novel derivatives of 2-imino-2,5-dihydrofuran-3-carboxamides containing a thiourea residue have been synthesized by the reaction of...     

<Superscript>13</Superscript>C-<Superscript>13</Superscript>C spin-spin coupling constants in structural studies: XLII. Stereochemical study on functionalized 2,5-dihydrofuran-2-imines

The configurations and conformations of twelve 5-imino-2,5-dihydrofuran-3-carboxamides and 5-imino-2,5-dihydrofuran-3-amines were determined by analysis of the experimental ¹³C-¹³C coupling constants and those calculated by nonempirical methods, as well as by quantum-chemical calculations of the total energies and optimization of geometric parameters of preferential conformations at the MP2/6-311G** level. All the examined compounds were found to be formed and to exist in solution as individual Z isomers with orthogonal orientation of the amino and dialkylamino groups and s-trans orientation of the carbamoyl group in the ring with restricted internal rotation about the C(O)-N bond.     

Synthesis and some transformations of bicyclic γ-lactones with a fused cyclopropane ring

Reductive cyclization of 4-hydroxymethyl-5,5-dimethyl(or pentamethylene)-2,5-dihydrofuran-2-ones by the action of sodium tetrahydridoborate gave bicyclic compounds in which the lactone ring is fused to a cyclopropane ring. Hydrolysis of the products with aqueous sodium hydroxide resulted in the formation of the corresponding disodium cyclopropane-1,1-dicarboxylates, which reacted with alkyl halides to produce the diesters. Acid hydrolysis of the fused systems was accompanied by opening of the cyclopropane ring with formation of 4-chloromethyl-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylic acid.     

Cyanoacetylene and Its Derivatives: XXXII. Addition of Ammonia and Methylamine to 4-Hydroxy-4,4-diphenyl-2-butynenitrile

Nucleophilic addition of ammonia (25% aqueous solution) and methylamine to 4-hydroxy-4,4-diphenyl-2-butynenitrile occurs under mild conditions to afford 4-amino(or methylamino)-2,5-dihydro-5,5-diphenyl-2-iminofurans. 4-Hydroxy-4,4-diphenyl-2-butynenitrile in anhydrous liquid ammonia gives rise to 3-amino-4-hydroxy-4,4-diphenyl-2- butenenitrile which is quantitatively converted into the corresponding iminodihydrofuran or iminodihydrofuran hydrochloride in the presence of 10 wt % of KOH or gaseous hydrogen chloride. 4-Amino- and 4-methylamino-2-iminofurans react with 4-hydroxy-4-methyl-2-pentynenitrile to give 3-(4-amino- and 4-methylamino-5,5-diphenyl-2,5-dihydrofuran-2-ylideneamino)-4-hydroxy-4-methyl-2-pentenenitriles.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 64–69.Original Russian Text Copyright © 2005 by Mal’kina, Sokolyanskaya, Kudyakova, Sinegovskaya, Albanov, Shemyakina, Trofimov.     

Reactions of Ethyl 2-Amino-5-(2-aryl-2-oxoethylidene)- 4-oxo-4,5-dihydrofuran-3-carboxylates and 2-Amino-5-(2-aryl- 2-oxoethylidene)-4-oxo-4,5-dihydrofuran-3-carbonitriles with Alcohols

Ethyl 2-amino-5-(2-aryl-2-oxoethylidene)-4-oxo-1H-4,5-dihydrofuran-3-carboxylates and 2-amino- 5-(2-aryl-2-oxoethylidene)-4-oxo-1H-4,5-dihydrofuran-3-carbonitriles reacted with alcohols in the presence of a catalytic amount of concentrated aqueous HCl to give the corresponding 5-alkoxy-2-amino-5-(2-aryl-2- oxoethyl)-4-oxo-1H-4,5-dihydrofuran-3-carboxylic acid derivatives. A probable reaction mechanism was proposed on the basis B3LYP/6-311G(d) quantum chemical calculations.     

Methanolysis and hydrolysis of derivatives of methyl 2,5- and 4,5-dihydrofuran-2-carboxylates

Methyl 2,5-dimethoxy-2,5-dihydrofuran-2-carboxylate is formed in the reaction of HCl-CH₃OH with methyl 5-nitro-2-acetoxy-2,5-, 5-nitro-4-acetoxy-4,5-, and 2,5-diacetoxy-2,5-dihydrofuran-2-carboxylates, whereas methyl 2,5-dioxo-3-pentenoate bis(2,4-dinitrophenylhydrazone) and 4-oxo-2-penten-1,5-dioic acid 2,4-dinitrophenylhydrazone are isolated in the presence of 2,4-dinitrophenylhydrazine. Methyl 5-nitrofuran-2-carboxylate is formed by treatment of methyl 5-nitro-2-acetoxy-2,5-dihydrofuran-2-carboxylate with aqueous solutions of acetic or phosphoric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1603, December, 1977.     

Cyanoacetylene and Its Derivatives: XXVII. 5,5-Dialkyl-4-azido-2,5-dihydrofuran-2-imine

The reaction of 3-azido-4-hydroxy-2-alkynenitriles with hydrogen chloride is accompanied by intramolecular ring closure with formation of 5,5-dialkyl-4-azido-2,5-dihydrofuran-2-imine hydrochlorides which can be converted into the corresponding free bases by the action of potassium carbonate in ethanol.     

Spiro heterocyclization of 4-aryl-4-oxobutane-1,1,2,2-tetracarbonitriles to 3H-pyrrole derivatives, 2-oxa-7-azaspiro[4.4]nona-3,6,8-trienes

4-Aryl-3-methyl-4-oxobutane-1,1,2,2-tetracarbonitriles reacted with morpholine to give 8-amino-3-aryl-1-imino-4-methyl-6-(morpholin-4-yl)-2-oxa-7-azaspiro[4.4]nona-3,6,8-triene-9-carbonitriles.     

Mechanism and selectivity of radical alkylation of 3,4-Dichloro-2,5-dihydrofuran-2,5-dione

The mechanism of radical alkylation of 3,4-dichloro-2,5-dihydrofuran-2,5-dione with cyclohexane and 2,3-dimethylbutane follows an addition-elimination pattern with reversible formation of alkyl radicals. The proposed kinetic scheme takes into account the possibility for isomerization of primary 2,3-dimethylbutane radicals into tertiary and is consistent with the experimental data. The regioselectivity of the process is linearly related to the concentration of hydrogen chloride, so that the rate constant for the addition of primary 2,3-dimethylbutane radical to 3,4-dichloro-2,5-dihydrofuran-2,5-dione may be estimated. Effective procedures for the synthesis of 3-chloro-4-(2,3-dimethylbut-2-yl)-, 3-chloro-4-cyclohexyl-, and 3,4-dicyclohexyl-2,5-dihydrofuran-2,5-diones have been proposed.     

Reaction of oligomethylene di(3-oxobutanoate) with 1,1-disubstituted alkenes and molecular oxygen in the presence of manganese(II and/or IE) acetate

The reactions of 1,1-disubstituted ethenes with oligomethylene di(3-oxobutanoate) in the presence of manganese(II and/or III) acetate and atmospheric oxygen yielded an ω-(3-oxobutanoyloxy)alkyl 6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylate, oligomethylene di(6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylate)s, ω-hydroxyalkyl 6,6-diaryl-3-hydroxy-3-methyl-1,2-dioxane-4-carboxylates, an ω-(3-oxobutanoyloxy)alkyl 5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylate, oligomethylene di(5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylate)s, ω-hydroxyalkyl 5,5-diaryl-2-methyl-4,5-dihydrofuran-3-carboxylates, and an ohgomethylene diester bearing a substituted 1,2-dioxane ring and a substituted 4,5-dihydrofuran ring. The reaction of the 1,2-dioxan-3-ols with acid gave the corresponding compounds bearing furan rings. The reaction of 1,1,6,6-tetraaryl-1,5-hexadienes with oligomethylene di(3-oxobutanoate) in the presence of manganese(III) acetate yielded macrocyclic diesters bearing two 4,5-dihydrofuran rings.     

1,3-Dipolare Cycloaddition aromatischer Nitril-ylide und Nitril-oxide an Dicyan und Diazocyanide

1,3 Dipolar Cycloaddition of Aromatic Nitrile Ylides and Nitrile Oxides with Cyanogen and Diazocyanides Nitril ylides 2 generated from the imidoyl chlorides 1 react with cyanogen and aryldiazocyanides to 2,5(4)-dia-ryl-1H-imidazole-4(5)-carbonitriles 3a , b or 5(4)-(arylazo)-2,4(5)-diaryl-1H-imidazoles 4a and 2,3,5-triaryl-2,3-dihydro-1H-1,2,4-triazole-1-carbonitriles 5a – f , respectively (Scheme 1). Reactions of benzonitrile oxides 7 with these dipolarophiles lead to 3,3′-diaryl-5,5′-bi[1,2,4]oxadiazoles 8a – c or 3-aryl-5-(arylazo)-1,2,4-oxadiazoles 9a – j (Scheme 2).