Studies in the furan series. XXXIX. Reaction of furan and 2-methylfuran with acrylonitrile

Furan undergoes a diene-synthesis type of reaction with acrylonitrile to give stereoisomeric 3, 6-endoxotetrahydrobenzonitriles whose configurations are established by PMR spectra. 2-Methylfuran undergoes a similar reaction with acrylonitrile. Some aspects of the relationship between the diene substitution reaction and substitutive addition in the furan series are considered.Communication XXXVIII, see [1].     

Reissert compound studies. XXXV. Acid-catalyzed condensations of the phthalazine reissert compound and condensations of phthalazine reissert compound salt

The phthalazine Reissert compound hydrofluoroborate undergoes condensation with alkynes to give pyrrolo[2,1-α]phthalazines and with alkenes to give 2-(1-phthalazyl)pyrroles. The phthalazine Reissert compound undergoes acid catalyzed condensations with some alkenes but the intermediate is of sufficient stability to be isolated. This same type of intermediate can also be isolated in the acid-catalyzed hydrolysis of the phthalazine Reissert compound.     

On the reaction of cyclopropanone hemiketal with Wittig reagents

Upon treatment with methylmagnesium iodine and benzylidenephosphoranes the ethyl hemiketal of cyclopropanone undergoes Wittig olefination.     

Stereochemical aspects of the reaction of dialkyl phosphates with amine in the presence of triphenylphospine and carbon tetrachloride

Activation of P-chiral dialkyl phosphates with triphenylphosphine-carbon tetrachloride involves intermediate phosphonium salt 1 which undergoes nucleophilic attack by aniline or pyridine with inversion of configuration at the chiral phosphorus atom.     

Studies on the stability of the cyclobutane β-aminoacid skeleton: a cautionary tale

The 2-amino-1-cyclobutanecarboxylic acid skeleton undergoes facile retro-Mannich type ring opening in solution, which may lead to unexpected by-products during its synthesis or manipulation.     

Example of a Facile Substitution of the Hydroxy Group Due to the Anchimeric Assistance of Selenium

Russian Journal of Organic Chemistry - Bis(2-bromo-3-hydroxypropyl) selenide was synthesized in quantitative yield by the reaction od selenium bromide with allyl alcohol. The product undergoes...     

烟酸的电化学行为与测定

用循环伏安法研究了不同支持电解质溶液中烟酸的电化学行为。烟酸在玻碳电极表面有良好的电化学响应信号。在碱性介质中,烟酸被不可逆氧化,氧化产物具有电活性,可发生准可逆氧化还原反应;在酸性介质中,烟酸发生两步准可逆氧化还原反应。结合红外、紫外光谱分析,提出了烟酸在不同酸度的介质中的电化学反应历程。并根据－０．１３Ｖ处的氧化峰电流与烟酸浓度的关系,提出了电化学测定烟酸的新方法     

1,3,5-Triarylpent-2-en-1,5-diones for the colorimetric sensing of the mercuric cation

The 1,3,5-triarylpent-2-en-1,5-dione group selectively undergoes cyclisation and changes its colour from yellow to magenta upon coordination of Hg2+ on a remote site.     

Solid State Nuclear Magnetic Resonance Studies of the Thermochromic Phase Transition of the Polydiacetylene from the Bis-n-Propylurethane of 5,7-Dodecadiyne-1,12-diol

The polydiacetylene (PDA) from the bis-n-propylurethane of 5,7-dodecadiyne-1,12-diol (PUDO) undergoes a first order phase transition near 135°C that is associated with a color change from blue at temperatures below the transition to red at temperatures above the transition. We have studied PDA-PUDO by solid state ¹³C nuclear magnetic resonance (NMR) spectra using cross polarization and magic angle spinning (CP-MAS) techniques at temperatures between 25° and 140°C. As observed previously, the acetylene carbon shift moves up field as the temperature is raised above the transition temperature. In addition, near 130°C, the oxymethylene carbon shows 3 resonances, indicating multiple side chain conformations as the PDA undergoes the phase transition.     

Cycloaddition Reactions of an Active Cyclic Phosphane/Borane Pair with Alkenes,Alkynes, and Carbon Dioxide

The active six-membered cyclo-FLP 6 undergoes a rapid P/B addition reaction to carbon dioxide. At elevated temperature, the resulting heterobicyclo[2.2.2]octane derived product 7 undergoes ring opening and equilibrates with the cyclotetramer (7)₄ . In the large macrocyclic structure, four monomeric six-membered cyclo-FLP units are connected by four CO₂ molecules to form the supramolecular ring system. The P/B cyclo-FLP 6 undergoes a variety of additional cycloaddition reactions.     

Acylhydroperoxide oxidations of the anticancer agent hexamethylmelamine

The clinically effective anticancer agent hexamethylmelamine undergoes an unusual acylhydroperoxide oxidative transformation to give the novel product 2,4-bis(dimethylamino)-6-[(dimethylamino)oxy]-1,3,5-triazine.     

Ferrocene derivatives XXVIII. The metallation of phenylazoferrocene and the synthesis of phenylazocyclopentadienyl derivatives of other metals

Phenylazoferrocene undergoes nickelation and palladation exclusively on the phenyl group. Lithium phenylazocyclopentadienide has been converted into derivatives of Mo, Mn, Fe, Ru and Rh.     

On the stability of furanopyrimidin-2-one bases in oligonucleotides

The fluoresceinated furanopyrimidin-2-one nucleobase incorporated into an oligonucleotide undergoes unexpectedly facile hydrolytic ring-opening in aqueous buffer at slightly elevated temperatures.     

Desulfation and rearrangement of tigemonam to an isoxazolidin-5-one and the synthesis of the rearrangement product

The β-lactam antibiotic Tigemonam 2 undergoes desulfation to the N-hydroxyazetidinone 4 , which rearranges to the isoxazolidin-5-one 6 . The structure of the rearrangement product 6 was confirmed by synthesis.     

Conclusive evidence of the trapping of primary ozonides

[reaction: see text] Anomalous ozonolysis of strained bicyclic allylic alcohols yields alpha-hydroxymethyl ketones. The proposed mechanism involves an unusual trapping of the primary ozonide that undergoes a Grob-like fragmentation instead of dissociating into the Criegee intermediates.     

Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine

The electrochemical oxidation behaviour at boron doped diamond and glassy carbon electrodes of the sulphur-containing amino acids cysteine and methionine, using cyclic and differential pulse voltammetry over a wide pH range, was compared. The oxidation reactions of these amino acids are irreversible, diffusion-controlled pH dependent processes, and occur in a complex cascade mechanism. The amino acid cysteine undergoes similar three consecutive oxidation reactions at both electrodes. The first step involves the oxidation of the sulfhydryl group with radical formation, that undergoes nucleophilic attack by water to give an intermediate species that is oxidized in the second step to cysteic acid. The oxidation of the sulfhydryl group leads to a disulfide bridge between two similar cysteine moieties forming cysteine. The subsequent oxidation of cystine occurs at a higher potential, due to the strong disulfide bridge covalent bond. The electro-oxidation of methionine at a glassy carbon electrode occurs in two steps, corresponding to the formation of sulfoxide and sulfone, involving the adsorption and protonation/deprotonation of the thiol group, followed by electrochemical oxidation. Methionine undergoes a one-step oxidation reaction at boron doped diamond electrodes due to the negligible adsorption, and the oxidation also leads to the formation of methionine sulfone.     

A novel retro-ene reaction the fragmentation of N-Benzyl-2-benzoyl-2-methylpropanimine

N-Benzyl-2-benzoyl-2-methylpropanimine treated with nucleophiles undergoes a fragmentation reaction that can be envisaged as a retro-ene reaction via the formation of an intermediate hemiketal.     

Ion/molecule reactions of the protonated serine octamer

The protonated homochiral octamer of serine exchanges all 33 of its labile hydrogens with CH(3)OD and undergoes ligand switching reactions with amines in a quadrupole ion trap mass spectrometer.     

An unusual rearrangement of photolysis of the enol acetate of 4-thiochromanone

The enol acetate from 4-thiochromanoneon photolysis undergoes ring opening, apparently involving a novel (1,5)-acyl migration from oxygen to sulfur, to give 1-(2-acetylthiophenyl)propen-1-one.     

Synthesis and diels-alder reactions of 5,5-dicyanocyclopentadiene: regioselective synthesis of 1,5-disubstituted-1,3-cyclohexadienes

5,5-Dicyanocyclopentadiene, readily prepared in three steps from commercially available cis-1,4-dichloro-2-butene, undergoes Diels-Alder reactions with a number of dienophiles to give 5-substituted 7,7-dicyanobicyclo[2.2.1]hept-2-enes with high endo-selectivity. The adduct produced with methyl acrylate undergoes base-induced retro-Michael reactions to give 1-carbomethoxy-5-dicyanomethyl-1,3-cyclohexadiene.