Reactions of 1-aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones with some nucleophilic reagents

Reactions of 2-bromo-1-phenyl- and 2-bromo-1-(4-methylphenyl)-3,4,4-trichlorobut-3-en-1-ones with morpholine and diethylamine are accompanied by prototropic allylic rearrangement, leading to 3-amino-1-aryl-2-bromo-4,4-dichlorobut-2-en-1-ones as mixtures of E and Z isomers. The title compounds react with hydrazine, hydroxylamine, and thiourea to give the corresponding 5-aroyl-4-methoxypyrazoles, 3-aryl-5-hydroxyiminomethyl-4-methoxyisoxazoles, and 2-amino-4-aryl-5-trichlorovinylthiazoles.     

Synthesis of some schiff bases of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones

Summary The reaction of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones (Ar=p-tolyl, 1,1-biphenyl-4-yl or thienyl) with aniline and substitutedo-phenylenediamine (R=H, CH₃ or Cl) yields a series of new Schiff bases2a–f in 51–72% yield. Bromination of1a gave the 5-bromo derivative1c, while the compounds1a,1b,2b,2e, and2f were converted into 2,6-diaryl-4H-pyran-4-ones3a–c. All products have been fully characterized.

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Synthese von Schiff'schen Basen von 3-Aroyl-6-aryl-4-hydroxy-2H-pyran-2-onen

Zusammenfassung Die Reaktion von 3-Aroyl-6-aryl-4-hydroxy-2H-pyran-2-onen (Ar=p-Tolyl, 1,1-Biphenyl-4-yl oder Thienyl) mit Anilin und substituierteno-Phenylendiaminen liefert neue Schiff'sche Basen2a–f/bd in 51–72% Ausbeute. Bromierung von1a gab das 5-Bromderivate1c, während die Verbindungen1a,1b,2b,2e und2f in 2,6-Diaryl-4H-pyran-4-onen3a–c übergeführt wurden. Alle Produkte wurden voll charakterisiert.

     

A convenient method of synthesis of mesomorphic 2,5-disubstituted cyclohexan-1-ones by a catalytic reduction of 3,6-disubstituted cyclohex-2-en-1-ones

The preparation of trans-2,5-disubstituted cyclohexan-1-ones from 3,6-disubstituted cyclohex-2-en-1-ones by reduction with hydrogen in the presence of palladium on carbon in a basic medium is described. The nature of the mesomorphic phases together with some physical properties of single compounds and of nematic mixtures comprising them are reported. Mesogens containing the trans-2,5-disubstituted cyclohexan-1-one ring show a small negative dielectric anisotropy and a low birefringence.     

Ring-transformation reactions of 5-hydroxy-2-oxabicyclo[3.2.0]-heptan-4-ones and 5-hydroxy-2-oxabicyclo[3.2.0]hept-6-en-4-ones

Dehydrochlorination of chlorinated 5-hydroxy-2-oxabicyclo[3.2.0]heptan-4-ones, 3a-c, which were obtained from the photo[2+2]cycloadditions between 4-hydroxy-3(2H)-furanone 1 and chloroethylenes, with triethylamine gave 2-ethenyl-3(2H)-furanones 4a,b or 2-(2-cyanoethyl)-3(2H)-furanone 4c. 2-Oxa-bicyclo[3.2.0]hept-6-en-4-ones 7 being [2+2]cycloadducts between 1 and acetylenes gave 2,3-dihydro-3-oxooxepin derivatives 8 by electrocyclic rearrangement.     

The meyer-schuster rearrangement and hydrohalide addition of 3-alkynyl-3-hydroxy-1H-isoindol-1-ones

Treatment of N-methyl and N-phenylphthalimide with appropiate lithium acetylides in tetrahydrofuran obtained the acetylenic alcohols 2a through 2h . These compounds, when subjected to mildly acidic hydrolysis conditions in aqueous organic solvents, underwent Meyer-Schuster rearrangement to yield the α,β-unsaturated carbonyl compounds 4a through 4h which were determined to have the E configuration. The phenyl ethynyl analogs of series 4 underwent hydrohalide addition when treated with hydrogen halides in water solution.     

Reactions of 4-acyl-1-alkoxyaryl-5-aryl-3-hydroxy-2,5-dihydro-1H-pyrrol-2-ones with nucleophilic reagents

4-Acetyl-1-alkoxyaryl-5-aryl-3-hydroxy-2,5-dihydro-1H-pyrrol-2-ones reacted with amines to give 1-alkoxyaryl-5-aryl-4-(1-R-aminoethylidene)pyrrolidine-2,3-diones. Reactions of amines with 4-benzoyl-substituted analogs involve nucleophilic attack on the C³ atom in the heteroring to produce the corresponding 3-R-amino-1-alkoxyaryl-5-aryl-4-benzoyl-2,5-dihydro-1H-pyrrol-2-ones. Reactions of the title compounds with hydrazine hydrate, regardless on the substituent on C₄, afforded 4-aryl-3-methyl(phenyl)-5-[2(4)-methoxyphenyl]-4,6-dihydropyrrolo[3,4-c]pyrazol-6-ones.     

Azoles and azines: CXXVIII. Reaction of 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones with 6-bromo-4-oxo-4H-chromene-3-carbaldehyde

Russian Journal of General Chemistry -     

Photochemical rearrangement of 8-oxabicyclo[3.2.1]oct-6-en-2-ones

Irradiation of 8-oxabicyclo[3.2.1]oct-6-en-2-ones results in a 1,3-acyl rearrangement. The initial photoproduct undergoes a subsequent reaction involving hydrogen transfer followed by intramolecular cycloaddition of a ketene intermediate.     

The carbon-13 nuclear magnetic resonance spectra of some α-spirocyclopropyl ketones and related cyclohex-2-en-1-ones and 2-ethylidenecyclohex-3-en-1-ones

The ¹³C NMR spectra of a series of β,γ-unsaturated α-spirocyclopropylcyclohexanones and saturated α-spirocyclopropylcycloalkanones have been analyzed and compared with the spectra of diethyl cyclopropanedicarboxylate and a corresponding spiro acylal. The chemical shifts of the cyclopropane methylene carbons are correlated with spiroactivation of the cyclopropane ring to nucleophilic attack. In the case of the saturated spiro ketones these chemical shifts can also be correlated with their photochemistry. In the SFORD spectra of the spiro ketones the signals of the cyclopropane methylene carbons appear as complex multiplets: this is attributed to second-order coupling resulting from strong coupling between the vicinal cyclopropane protons. The ¹³C NMR spectra of a series of related cyclohex-2-en-1-ones and 2-ethylidenecyclohex-3-en-1-ones have also been analyzed; the chemical shift assignments for the latter corroborate the configurational assignments made on the basis of ¹H NMR spectroscopy.     

Reaction of ethyl γ-bromo-β-methoxycrotonate with carbonyl compounds. Synthesis of 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones and 3-substituted 3-pyrazolin-5-ones

Ethyl β-methoxycrotonate I reacts with substituted carbonyl compounds II in benzene to give 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones III. The reaction of IIIa and j with hydrazine hydrate in ethanol leads to 3-[(1′-thienyl-1-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVa) and 3-[1′-styryl-1′-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVj) in good yields. The structure of the products were assigned and confirmed on the basis of their elemental analysis and the electronic absorption, infrared and nmr spectra.     

Catalytic synthesis of 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) and 3,3,6,6-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones

Condensation of substituted benzaldehydes of vanillin series with dimedone in methanol solution in the presence of catalytic quantities of triethylamine afforded 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones. By catalytic cyclization of the latter in boiling benzene in the presence of sulfo cation exchanger FIBAN K-1 as catalyst 3,3,6,6-trimethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones were synthesized.     

Synthesis of 3-alkyl-8-substituted- and 4-hydroxy-8-substituted-2,3,4,5-tetrahydro-1H-2-benzazepines

Based on the Schmidt reaction and an iodolactone ring expansion reaction, two different synthetic routes to substituted 2,3,4,5-tetrahydro-1H-2-benzazepines were developed. The Schmidt reaction on 2,3-dihydro-2H-1-naphthalenone ( 1 ) gave 3 , the product resulting from the alkyl group migration, as the major product instead of the tetrazole 2. This prompted the investigation of the Schmidt reaction on aromatic ketones 8 and 12. The product 9 due to alkyl group migration was the major product of the Schmidt reaction on 2-methyl-3,4-dihydro-2H-1-naphthalenone ( 8 ). The β-keto diester 12 gave a mixture of decarb-oxylated lactams after the Schmidt reaction. In this case, the lactam 13 resulting from the migration of the aromatic ring dominated over the other lactam 14. When lactam 14 was subjected to nitration, a single regioisomer was produced and transformed to the bromo alcohol 19. The other approach was based on the single pot ring expansion of the iodolactone 22 to the lactam 23 in the presence of methanolic ammonia. The iodolactone 22 was readily prepared from 2-allylbenzoic acid.     

4-Hydroxy-2-quinolones. 39. Structure of 6-bromo-4-hydroxy-1-isoamyl-2-oxo-3-quinolinecarboxylic acid

S-(–)-1-phenylethylamide of 6-bromo-4-hydroxy-1-isoamyl-2-oxo-3-quinolinecarboxylic acid was synthesized. X-ray diffraction investigation of this product was carried out to determine its absolute configuration.For communication 38, see ref. [1].National Pharmaceutical Academy of Ukraine, 310002 Kharkov, Ukraine Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 64–69, January, 2000.     

Thermal rearrangement of some 3-substituted-2,1-benzisoxazoles

3-(Phenyliminomethyl)- and 3-arylazo-2,1-benzisoxazoles undergo thermal rearrangement to 3-phenylquinazolin-4-one and 3-aryl-1,2,3-benzotriazin-4-ones, respectively.     

A general approach for the synthesis of 5-substituted-4-amino-pyrrolidin-2-ones and 5-substituted-4-amino-3-pyrrolin-2-ones

Short stereoselective syntheses of both 5-substituted-4-amino-pyrrolidin-2-ones and 5-substituted-4-amino-3-pyrrolin-2-ones from natural α-amino acids are described.     

A new synthesis of 4-methoxy-cyclopent-2-en-1-ones

4-methoxy-cyclopent-2-en-1-ones $\text{6}$ are easily obtained through a simple procedure involving in the key-step the conversion of 2-furylcarbinols $\text{1}$ into 1,1,2-trimethoxy-al-kan-4-ones $\text{3}$, a masked form of 1,4-dicarbonyl compounds, by treatment with Amberlyst H15 in methanolic solution. Then, the regeneration of the aldehydic function and a base-catalysed aldolic condensation lead in high yields to the final products $\text{6}$.