Olesya A. Shemyakina

A Domino Reaction of α,β-Acetylenic γ-Hydroxy Nitriles with Arenecarboxylic Acids: An Unexpected Facile Shortcut to 4-Cyano-3(2H)-furanones

An unexpected facile domino reaction of alpha,beta-acetylenic gamma-hydroxy nitriles with arenecarboxylic acids (Et(3)N, MeCN, 20-25 degrees C, 48 h) affords 4-cyano-3(2H)-furanones in 67-86% yield. The reaction is triggered by the addition of an arenecarboxylic acid to a triple bond, followed by the domino reaction sequence: intramolecular transesterification-enol formation and Claisen condensation of the ketoacetonitrile tautomer with ester functional group.

Expedient Access to Functionalized Furan/3(2H)-furanone Ensembles via Microwave-Assisted Domino Reactions

Abstract A one-pot linkage between furan and 3(2H)-furanone rings has been effected via the microwave-assisted Et3N-catalyzed domino condensation of the furan and benzofuran carboxylic acids with available cyanopropargylic alcohols (MeCN, 100 °C, 1.2 atm, 2–17 h). Despite involving a number of C-H-forming/breaking steps, the assembly is chemoselective and the final products, 5-(2-furyl)-3(2H)-furanones, are formed in 59–96% yields. GRAPHICAL ABSTRACT

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.

13C-13C 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.

Cyanoacetylene and Its Derivatives: XXXIII. One-Pot Stereoselective Synthesis of Bis-iminodihydrofurans from 4-Hydroxy-4-methyl-2-pentynonitrile and Aromatic Amines

Abstract4-Hydroxy-4-methyl-2-pentynonitrile reacts with aniline, N-methylaniline, and 2-naphthylamine under mild conditions (20–80°C) to afford the corresponding 4-arylamino-2-(2-imino-5,5-dimethyl-2,5-dihydro-4-furylimino)-5,5-dimethyl-2,5-dihydrofurans in one preparative step. According to the X-ray diffraction data, both imino groups in the products have syn configuration with respect to the ring oxygen atom.

One-pot stereoselective tandem assembly of functionalized furan-3(2H)-one from γ-hydroxyalk-2-ynenitriles and 3-hydroxybenzoic acid

Abstractγ-Hydroxyalk-2-ynenitriles react chemo-, regio-, and stereoselectively with 3-hydroxybenzoic acid under mild conditions (Et3N, MeCN, 20–25°C, 48–144 h) giving 4-oxo-2-{3-[(1Z)-(1-cyanoalk-1-en-2-yl)oxy]-phenyl}-4,5-dihydrofuran-3-carbonitriles in 60–75% yields. The reaction opens a simple path to a new group of furan-3(2H)-one derivatives with pharmacophore functions.

Cyanoacetylene and Its Derivatives: XXXIV. Nucleophilic Addition of Tetrazole to Cyanoacetylenes

Nucleophilic addition of tetrazole to 4-hydroxy-4-alkyl-2-alkynonitriles and to 3-phenyl-2-propynonitrile occurred regiospecifically and afforded E-, Z-4-hydroxy-4-methyl-3-tetrazolyl-2-alkenonitriles and 3-tetrazolyl-3-phenyl-2-propenonitrile [20–40°C, 13–50 h, 4–15 wt% MOH (M = Na, K), THF (or DMSO)] in up to 69% yield. The attempt to perform cyclization of the hydroxy-containing adducts into iminodihydrofurans (KOH, ethanol, 23-25°C) resulted in vinyl nucleophilic substitution of the tetrazole moiety by an ethoxy group.

Cycloadducts of methyl hydroxyalkynoates and DBU: Transformation into tethered furan-2(5 H )-one and caprolactam structures

Cycloadducts of 1,8-diazabicyclo[5.4.0]undec-7-ene and methyl 4-hydroxyalk-2-ynoates, octahydro-5H,9H-[1,3]oxazolo[2′,3′: 2,3]pyrimido[1,2-a]azepines, in the presence of potassium hydroxide in aqueous ethanol were converted to structures in which furan-2(5H)-one and caprolactam rings are linked to each other through an aminopropane tether.

Chemo- and regioselective modification of l-histidine with tertiary cyanopropargylic alcohols

Abstractl-Histidine chemo- and regioselectively reacts with tertiary cyanopropargylic alcohols (4,4-di-alkyl-4-hydroxybut-2-ynenitriles) under mild conditions (water, 6.4 wt.% NaOH, 5—15 °C, 72—175 h) with the formation of new “unnatural” amino acids containing an iminodihydrofuran substituent in the amino group (50—70% yields).