Synthesis of Vinyl and β-Phthalimido Ketones

Vinyl ketones are prepared by reaction of an aldehyde with a vinyl Grignard reagent followed by a Swern oxidation. β-Phthalimido ketones are then obtained by 1,4-addition of phthalimide.     

Stereoisomerism ofβ-polyfluoroalkyl-α,β-enones

-Polyfluoroalkyl-,-enones formed in the E,Z form are converted by the action of atmospheric oxygen into a 937 mixture of E,Z and Z,E isomers in the dark and 6040 mixture of these isomers in the light. The Z isomer of 1-phenyl-4,4, 4-trifluoro-2-buten-1-one was isolated preparatively for the first time and its E conformation relative to the C-C bond was established. The Z,E isomer spontaneously transforms into the indicated equilibrium mixtures.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1685–1689, July, 1991.     

A Convenient Synthesis of β-Chloro, β-Methylthio α,β-Unsaturated Ketones from β-Oxodithioesters

The reaction of β-oxodithioesters with the Vilsmeier-Haack reagent prepared from POCl₃ and DMF provide β-chloro, β-methylthio α,β-unsaturated ketones in good yields.     

Synthesis of pyrazolines by the reactions ofα,β-enones with diazomethane and hydrazines (review)

The first representatives of pyrazolines were synthesized in the last century. These nitrogen-containing heterocyclic compounds became important in the development of different bioactive substances. For this reason, various procedures have been worked out for their synthesis. In the present article we summarize those synthetic methods providing 1- or 2-pyrazolines by the reactions of ,-unsaturated ketones with diazomethane or hydrazine derivatives.Department of Organic Chemistry, Kossuth Lajos University, Egyetem ter I, H 4010 Debrecen, Hungary. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 747–759, June, 1997.     

Synthesis of β,β‘-Difluorinated and β,β’-F-Dialkylated Acetals

Using the phase transfer catalysis technique, a series of fluorinated acetals has been prepared, in basic medium, by action of dicholromethane on 2-mononfluorinated alcohols or 1-F-alkyl 2-fluoroethanols. The identification of these new acetals has been achived by the study cf their ¹H, 19F NMR and their mass spectra.     

Hypervalent Iodine in Synthesis XXX: Palladium-Catalyzed Reaction of Diaryliodonium Salts with β-substituted-α, β-enones

The reaction of diaryliodonium salts with β-substituted-α,β-enones in the presence of a palladium catalyst affords H_β-substituted products with excellent yields.     

Synthesis of α,β-Unsaturated Ketones via Enamines

Acylation of an enamine followed by acid hydrolysis constitutes the well-known Stork's reaction of synthesizing β-diketones.^1,2 This article reports that the acylated enamine 1 which corresponds to monoenamine of a β-diketone can be hydrogenated to a Mannich base 2 which on elimination by heating or treatment with acid yields the α, β-unsaturated ketone 3; further hydrogenation gives saturated ketone 4 in good yield (Scheme 1). A similar transformation effected by hydroboration has been reported by Montury and Góre.     

Synthesis of 1,3-Dioxolane Derivatives from β-Chlorolactic Acid and Ketones

2-Ethyl-2-methyl-5-methylene-1,3-dioxolan-4-one and 5-methylene-2,2-pentamethylene-1,3-dioxolan-4-one were synthesized by reaction of -chlorolactic acid with methyl ethyl ketone and cyclohexanone, respectively, followed by dehydrochlorination of intermediate 5-chloromethyl derivatives.     

α-Aminoxylation of Ketones and β-Chloro-α-aminoxylation of Enones with TEMPO and Chlorocatecholborane

Oxidation of various cyclic and acyclic ketones under mild conditions with chlorocatecholborane, a bulky pyridine base, and TEMPO to the corresponding α-aminoxylated products in good to excellent yields (52-99%) is described. For enones as substrates, products of a β-chloro-α-aminoxylation are obtained (70-89%).     

Synthesis and structure of alkyl-α-arylamino-β-bromo-β-nitroacrylates, new functionalized β-nitroenamines

New bromonitroenamine compounds, alkyl-2-arylamino-3-bromo-3-nitroacrylates, were synthesized and characterized using IR, UV, ¹H and ¹³C NMR spectroscopy, and X-ray analysis. Their molecules were found to have the E-configuration and to exist as highly conjugated structures. According to the X-ray analysis, in the ethyl-3-bromo-2-(p-bromophenylamino)-3-nitroacrylate molecule the bromonitroenamine moiety is almost planar, the ester group is located completely out of the C=C double bond plane, amino hydrogen and nitro oxygen atoms form an intramolecular hydrogen bond.     

Synthesis and reactivity of alkenyl- and alkynyl-substituted β,β-dihalo-and β,β,β-trichloroamines

β,β-Dihalo- and β,β,β-trichloroamines, obtained by Lewis acid-promoted Petasis-type reaction of α,α-dichlorinated and α,α,α-trichlorinated imines or reduction of α,α-dihaloaldimines, were subjected to a reactivity study and turned out to be remarkably stable compounds. In general, only the bases KO^tBu and NaOMe cause a 1,2-dehydrochlorination with formation of unsaturated α-chloroimines or unsaturated α,α-dichloroimines. Hydrolysis of the α-chloroimines with aqueous oxalic acid resulted in the formation of the corresponding unsaturated α-chloroketones. The reaction of simple β,β-dihaloamines with NaOMe and KO^tBu generated 2-haloprop-2-enylmines and 2,2-dimethoxypropylamines.     

Synthesis and structure of β-aryl-α-nitroacrylates

The method for preparation of ethyl α-nitrocinnamates by nitroacetic acid ester alkenylation with aromatic aldehydes in the presence of acetic acid and β-alanine has been modified. Structures of the prepared compounds have been proved by electronic, IR, ¹H, and ¹³C-{¹H} NMR spectroscopy (including heteronuclear correlation experiments ¹H-¹³C HMQC and ¹H-¹³C HMBC). In solution these compounds exist in the form of Z-isomer; the Z?E isomerization is observed in the case of the compound containing strong electron-donor group [N(CH₃)₂] at benzene ring.     

Synthesis and characterization of water-swellableα,β-polyasparthydrazide derivatives

The synthesis of a new crosslinked polymer by reaction of , -polyasparthydrazide and glutaraldehyde is reported. Different crosslinking degrees were obtained by varying the ratio between the aldehyde and the starting polymer. The crosslinked polymer was characterized by water swelling tests and thermal analysis. In particular, the crosslinking density and its effects on the glass transition temperature of the material were studied. Finally, the microstructure of the obtained polymer was observed using scanning electron microscopy.     

Synthesis and characterization of water-swellableα,β-polyasparthydrazide derivatives

, -polyasparthydrazide (PAHy) was crosslinked by glutaraldehyde to form water-swellable materials possessing a three-dimensional molecular network. Different crosslinking degrees were prepared varying glutaraldehyde/PAHy ratio and samples containing 5-fluorouracil were obtained by incorporating the drug into the polymer networks during the crosslinking reaction. All samples were characterized by swelling tests, thermal, x-ray and SEM analysis. Their microstructure was observed through scanning electron microscopy. Furthermore, for samples containing the anticancer drug,in vitro release studies were performed in pH 7.4 buffer solution.     

An Efficient One Pot Synthesis of α-Iodo-α,β-unsaturated Esters,Ketones and Nitriles via Arsonium Salts

A number of α-iodo-α,β-unsaturated compounds 3 were synthesized under mild conditions via corresponding readily available arsonium salts 1 in one pot reaction.     

Bromination of polyfluorinated α,β-enones

Polyfluoroalkyl-,-enones readily add Br₂ to give ,ß-dibromoketones. The latter are readily and regioselectively dehydrobrominated to -bromo-,-enones on treatment with K₂CO₃ or NEt₃ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2134–2136, December, 1993.     

Homologation of α,β-Ethylenic Ketones in Substituted β,γ-Ethylenic Ketones Using Phosphoniosilylation

Among the methods described (1–4) to prepare β,γ-unsaturated ketones 2, Warren (4) recommends the Wittig-Horner procedure involving β-acetalated diphenylphosphinoxides reagents |scheme 1 (i)|.     

Synthesis,Physicochemical Properties,and Structure of Heterocyclic β-Aminovinyl Ketones and Related Copper(II) Complex

Heterocyclic -aminovinyl ketones (HL) and the copper complex CuL₂ are synthesized and studied by IR and ¹H NMR spectroscopies. The crystal structure of one of the tautomeric HL molecules is determined by X-ray diffraction analysis. The crystals are triclinic: a = 9.261(6) Å, b = 9.448(6) Å, c = 11.310(5) Å, = 96.74(5)°, = 99.46(5)°, = 93.60(5)°, space group P . The compound has the form of a ketoamine tautomer. The structure contains intramolecular and intermolecular hydrogen bonds. The latter link the molecules into the center-symmetric dimers.     

Reactions of β-Sulfinyl α,β-Unsaturated Ketones with Dienes

β-Sulfinyl α,β-unsaturated ketones (2a-f) reacted in a regioselective manner with dienes such as butadiene (3a) and 1,3-pentadiene (3b) to give 1,4-cyclohexadiene derivatives (4-8) with the concomitant elimination of sulfenic acid, while the ketones (2a-c) reacted with cyclopentadiene (3c) to yield the norbornenes (9).