Reactions of Acylpyruvic Acids and 2,3-Dihydrofuran-2,3-diones with 2,3-Diaminopyridine

Acylpyruvic acids readily react with 2,3-diaminopyridine to form (Z)-3-acylmethylene-1H-3,4-di- hydropyrido[2,3-b]pyrazin-2-ones. 5-Aryl-2,3-dihydrofuran-2,3-diones which can be regarded as lactones derived from -enolized aroylpyruvic acids react with 2,3-diaminopyridine under mild conditions, yielding regioisomeric (Z)-2-aroylmethylene-4H-1,2-dihydropyrido[2,3-b]pyrazin-3-ones. The structure of the products and reaction chemoselectivity are discussed.     

Pyrrolidine-2,3-dione, 1-allylpyrrolidine-2,3-dione and 1-ethoxypyrrolidine-2,3-dione

Authentic pyrrolidine-2,3-dione has been prepared by two different routes. It is shown that the material previously reported is actually a hydrolysis product, 4-amino-2-oxobutyric acid. 1-Allyl- and 1-ethoxypyrroli-dine-2,3-dione have been prepared as N-protected pyrrolidine-2,3-diones potentially useful in synthesis.     

Electrochemical Synthesis of 2,3-Dimethyl-2,3-Dinitrobutane

Anodic oxidation of 2-nitropropane in a methanol solution of sodium iodide and hydroxide is found to produce 2,3-dimethyl-2,3-dinitrobutane with a yield of 65-70% under optimum conditions. Deceased.     

meso-四苯基-2,3-二氢卟啉-2,3-二醇的合成

研究了一种关于meso-四苯基-2,3-二氢卟啉-2,3-二醇的避免使用昂贵且剧毒的四氧化锇的合成方法,整个合成过程中所用试剂廉价易得,反应操作简单.该合成方法可同时得到顺、反两种目标产物异构体.     

First direct detection of 2,3-dimethyl-2,3-diphenylcyclopropanone

3,5-dihydro-3,5-dialkyl-3,5-diaryl-4H-pyrazol-4-ones stimulate interest as potential precursors for 2,3-diarylcyclopropanones. Photoreactions of trans-3,5-dihydro-3,5-dimethyl-3,5-diphenyl-4H-pyrazol-4-one were studied by continuous-wave (CW) and pulsed laser UV photolysis revealing an intermediate that undergoes rearrangement to form cis- and trans-1,3-dimethyl-1-phenyl-2-indanones with the yield of ca. 60%. Steady-state photolysis (254 and 350 nm excitation) in different solvents produced an intermediate cyclohexadiene as evidenced by UV/vis, IR, and 1H NMR spectra. In contrast, the nanosecond laser pulsed photolysis at 355 nm produced 2,3-dimethyl-2,3-diphenylcyclopropanone along with two products of retro-1,3-dipolar addition phenylmethylketene and 1-phenyldiazoethane. These can be observed by time-resolved IR (TRIR) spectroscopy as characteristic absorption bands at 1814, 2101, and 2038 cm-1, respectively. Similar retro-1,3-dipolar addition showed 1-phenyldiazoethane formed following flash photolysis of 1-pyrazoline (trans-4,5-dihydro-3,5-dimethyl-3,5-diphenyl-3H-pyrazol-4-ol). The formation of the corresponding cyclopropanone as well the products of retro-1,3-dipolar addition during photoreaction of starting pyrazol-4-one is directly confirmed by the nanosecond TRIR spectroscopy for the first time. On the basis of the CW and pulsed laser UV photolysis, a dynamic equilibrium between cyclopropanone and intermediate 2,4-diphenyl-3-pentanone-2,4-diyl (dimethyldiphenyloxyallyl) was proposed.     

2,3-Polymethylenequinolines

6-Chloro-9-arylamino-1,2,3,4-tetrahydroacridines were synthesized by intramolecular cyclization of arylamides of N-cyclohexylidene-4-chloroanthranilic acid. A number of new compounds were obtained, and their properties and biological activity were studied.See [1] for communication X.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 528–530, April, 1973.     

2,3-Dioxabicyclo

The photooxygenation of 1,4-cyclohexadiene (3) affords the diastereomeric hydroperoxy endoperoxides exo-4 and endo-4 and the diastereomeric hydroperoxides trans-5 and cis-5 in a ratio of 87:9:3. 5:0.5. Selective reduction of hydroperoxide group in the endoperoxides exo-4 and endo-4 in the presence of titanium tetraisopropoxide-diethyl sulfide gave the corresponding hydroxy endoperoxides exo-7 and endo-7, which on PCC oxidation leads to the phenol-derived keto endoperoxide 2. The triphenylphosphine deoxygenation of the keto endoperoxide 2 produces a 9:1 mixture of 1, 2- and 1,4-dihydroxybenzenes 10 and 11, while the CoTPP-catalyzed rearrangement affords the bisepoxide 12, malealdehyde (13), and beta-lactone 14. The mechanisms of these transformations are presented.     

Synthesis of 2,3-diaryl-1,4-diazolyl-2,3-epoxybutanes

2,3-Diaryl-1,4-diazolyl-2,3-epoxybutanes have been prepared from dimethylstilbenes. An efficient although neglected synthesis of the required olefins has been recovered from the literature. The target compounds show moderate antifungal activity.     

Synthesis of derivatives of pyrazine-2,3-dicarboxylic acids and pyrazine-2,3-dicarbonamides from 2,3-dichloroquinoxaline

The synthesis of dimethyl 2,3-dichloropyrazine-5,6-dicarboxylate from dichloroquinoxaline has been effected. The nucleophilic substitution reactions of the compound obtained have been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1548–1551, November, 1973.     

2,3-Dimercaptopropanol

Ohne Zusammenfassung     

Triplet-triplet absorption spectra of meso-tetraphenyl-2,3-tetranaphtho-2,3-tetraphenanthroporphins

Flash photolysis has been used to measure triplet-triplet (T-T) absorption spectra of meso-tetrapheny1-2,3-tetranaphthorphin and its zinc complex, and also zinc complexes of two isomers of meso-tetrapheny1-2,3-tetraphenanthrenopurphin. An analysis has been made of the inf Iuence of structural changes on the T-T absorption spectra.Institute of Physics, Academy of Sciences of the Belorussian SSR, Minsk. Scientific-Research Institute of Organic Intermediates and Dyestuffs, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. 1, pp. 105–108, January–February, 1991. Original article submitted February 24, 1989.     

Optical rotatory dispersion of 2,3-hexadiene and 2,3-pentadiene

The specific rotation of (P)-2,3-hexadiene (1) was measured as a function of wavelength for the gas phase, the neat liquid, and solutions. There was a surprisingly large difference between the gas phase and condensed phase values. The specific rotation was calculated using B3LYP and CCSD, and the difference in energy between the three low energy conformers was estimated at the G3 level. The Boltzmann-averaged CCSD-calculated rotations using the gauge independent velocity gauge representation, as well as the B3LYP values, are in agreement with the gas-phase experimental values. In order to avoid possible problems associated with the conformers of 1, 2,3-pentadiene (2) also was examined. Here again, there was a large difference between the gas-phase and condensed-phase specific rotations, with the CCSD velocity gauge (and B3LYP) results being close to the gas-phase experimental values. The possibility that 2,3-pentadiene could be distorted on going from the gas to liquid phase, thereby accounting for the effect of phase on the specific rotation, was examined via a Monte Carlo statistical mechanics simulation. No effect on the geometry was found. Specific rotations of 1 found in solutions were similar to those for the liquid phase, indicating that the phase difference was not due to association.