Synthesis of some substituted difluoronitroacetanilides and their reduction to substituted N-difluoronitroethylanilines

The synthesis of difluoronitroacetanilide and its p-methyl and m-methoxyl derivatives and their reduction by diborane in tetrahydrofuran to the corresponding N-difluoronitroethylanilines is described. Yields on the acetanilides ranged from 13 to 43% and on the anilines from 50 to 64%.     

Rearrangements of substituted 3-azidoazetidines: Unexpected formation of a substituted oxazole

Thermolysis of neat N-carboethoxy-3-azido-3-ethylazetidine ( 3 ) at 200° under argon produced the corresponding cyclic imine 4 (68% yield). Prolonged refluxing of a mixture of N-triflylazetidin-3-one ( 7 ), sodium azide, and titanium tetrachloride in acetonitrile solvent afforded recovered 7 (25% yield) along with a colorless microcrystalline solid, 8 , mp 104–105° (20% yield), whose structure was established unequivocally via application of X-ray crystallographic methods.     

取代邻苯二腈的合成

在室温条件下合成了一系列芳氧基邻苯二腈化合物,应用无素分析、1HNMR、IR确定了它们的结构,讨论了不同取代基对反应的影响.结果表明,酚的芳环上有推电子基时反应容易进行;酚的芳环上有拉电子基时反应慢或不反应.     

Thermochemistry of substituted pyrroles

The heats of solution of a series of substituted pyrroles in benzene, carbon tetrachloride, chloroform, DMF, and pyridine were measured by a calorimetric method at 298.15 K. The influence of substituents in the pyrrole molecule on the energy parameters of solvation by organic solvents is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 495–499, March, 1993.     

Nitration of substituted chromans

The nitration of substituted chromans has been studied and the structure of the nitro compounds has been confirmed by chemical and spectral data.     

Synthesis of substituted thienothiazoles

The action of sulfur monochloride on 2-amino-3-carboxy-5-phenylthiophene or 2-amino5-phenylthiophene hydrochloride gave 5-phenylthieno[2,3-d]-2-thioniathiazole chloride, which is converted to the corresponding hydrate on treatment with water. Heating of the thionium salt or its hydrate with carbon disulfide in an aqueous alcohol solution of aklaki gave 2-mercapto-5-phenylthieno[2,3-d]thiazole, which under the influence of dialkyl sulfates or on oxidation with potassium permanganate in alkaline media is converted, respectively, to S-alkyl derivatives or a 5-phenylthieno[2,3-d]thiazole-2-sulfonic acid salt. 2-Sulfo-3-alkylthieno[2,3-d]thiazolium betaines are obtained by heating the latter with alkylating agents. 2-Hydroxy-thieno[2,3-d]thiazoles were synthesized by hydrolysis of thienothiazole-2-sulfonic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 477–480, April, 1979.     

Enols of substituted cyanomalonamides

Twenty open-chain mono-, di-, and trialkyl and aryl-N-substituted cyanomalonamides R2R1NCOCH(CN)CONHR3 were prepared. In solution, signals for both amide and a single enol are mostly observed, despite the potential for E and Z isomeric enols. The equilibrium (KEnol) values between the amides and the enols were determined in different solvents by NMR spectra. They decrease on increasing the polarity of the solvent in the order CDCl3 approximately C6D6>THF-d8>(CD3)2CO>CD3CN>DMF-d7>DMSO-d6. For the R1R2NCOCH(CN)CONHR3 system when R1=R2=H, Me or R1=H, R2=Me, KEnol for R3 follows the order: C6F5>Ph>or=An>or= i-Pr>or= t-Bu, and for R1, R2:H, H>Me, H>Me, Me in all solvents. A unique feature is the appreciable % enol in DMSO-d6 when R1=R2=H, in contrast with enol systems with other electron-withdrawing groups (EWGs). Calculations (B3LYP/6-31G**) corroborate the higher KEnol values for less alkyl-substituted systems, showing that in the most stable conformer when R1=H, R2=R3=Me the N-hydrogens are closer to the CN group. The order of promoting substituents for enol of amide formation is CONH2>CO2CH2CF3>CO2Me>CONHMe. The solid-state structures of the isolated species, determined by X-ray crystallography, were either amides or enols, and a higher KEnol(CDCl3) value does not ensure a solid enol structure. In no system were both solid species isolated. The X-ray structures of the enols were temperature-dependent. In most cases, the difference between the O-H and O...H bond lengths at low temperature were appreciable, but they become closer at the higher temperature. Similar tendency for either the C=C/C-C or the C-O/C=O bonds was observed. This is ascribed to a hydrogen shift between two regioisomeric enols in an asymmetric double-well potential, which becomes faster at a higher temperature. Calculations show that the enol structures are nonsymmetrical, resembling the lower temperature structures, even when they are chemically symmetrical, but the energy differences between the two regioisomers are <1 kcal. The hydrogen bonds in the enol moiety are strong, with O...O distances <2.45 A, and are resonance-assisted hydrogen bonds. IR spectra in solution and the solid state qualitatively corroborate the NMR and X-ray structure determination.     

取代环戊二烯基锂芳酰化的研究

本文研究了由616-二烷基富烯与有机锂所制得取代环戊二烯基锂和芳酰氯的反应,合成了二十个未见文献报道的新富烯类化合物,并通过^1HNMR、IR和元素分析确定了它们的结构.     

Synthesis of substituted hydroxypyrazines

Conclusions A new method was developed for the synthesis of substituted hydroxypyrazine derivatives by reacting the hydrochlorides of-amino ketones with the acid chlorides of N-phthaloyl--amino acids in acetone in the presence of diethylaniline, and subsequent treatment of the intermediate N-(N-phthaloyl--aminoacyl)--amino ketones with aqueous sodium acetate solution at 100°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2417–2421, October, 1978.     

Synthesis of substituted pteridines

Conclusions The cyclocondensation of 2,5,6-triamino-4-oxo-3,4-dihydropyrimidine and tetraaminopyrimidine with butylthioacetone and 2-butylthiopropanal gives 7-methylpteridines, while the reaction of these pyrimidine derivatives with 2-phthalimidopropanal, 1,1-dibutoxyacetone, 1,1-dichloroacetone, and 1,1-dibromoacetone gives mixtures of 6- and 7-methylpteridines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–455, February, 1986.     

Synthesis of substituted N-aminoisomaleinimides

,-Disubstituted monohydrazides of maleic acid form stable aminoisomaleinimides on treatment with acetic anhydride in the presence of anhydrous sodium acetate. The structure of the products was confirmed by IR and PMR spectroscopy and by chemical methods.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 443–445, April, 1973.     

Synthesis of substituted thiabicyclanes

A simple preparative method for the synthesis of cis-1-thiahydrindan and cis-2-thiabicyclo[3, 3, 1]nonane has been developed. The method can be used to obtain substituted thiabicyclanes by a general method starting from 3-chloromethylcyclohexene. In the cyclization of 3 (-mercaptoethyl)cyclohexane both by an ionic and by a radical mechanism, a mixture of cis-1-thiahydrindan and cis-2-thiabicyclo [3,3,1] nonane in approximately equal amounts is formed.     

Unsymmetrically substituted benzothiazolyl-hydrazines

New unsymmetrically substituted hydrazines containing benzothiazole residues with substituents in the 6-position were obtained by the oxidative cyclization of substituted 1,4-diphenylthiosemicarbazides with potassium ferricyanide in alkaline aqueous alcoholic media. The reaction of these new hydrazines with trichloromethyl mercaptan gave N-(6-R-2-benzothiazolyl)-N-[p-(trichloromethylthioamidosulfonyl)phenyl]hydrazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 765–766, June, 1971.     

Hydrolysis of substituted 8-acetoxyquinolines

In the absence of metal ions, the hydrolysis of 2-methyl-8-acetoxyquinoline and of 5-chloro-8-acetoxyquinoline follow the same reaction paths as those of the parent ester 8-acetoxyquinoline, including an intramolecular catalysis by the quinoline nitrogen. Unlike the hydrolysis of the other esters, that of the 2-methyl compound appears not to be catalysed by metal ions, and this is consistent with the view that catalysis by a metal ion involves the formation of a 7-membered chelate structure.     

Two-photon excitation of substituted enediynes

Electronic spectroscopy of nine benzannelated enediynes and a related fulvene was studied under one-photon and two-photon excitation conditions. We utilize measured absorbance and emission spectra and time-resolved fluorescence decays of these molecules to calculate their radiative lifetimes and fluorescence quantum yields. The fluorescence quantum yields for the other compounds were referenced to the fluorescence quantum yield of compound 3 and used to determine relative two-photon absorption cross-sections. Further insight into experimental studies has been achieved using time-dependent density functional (TD-DFT) computations. The probability of two-photon absorption (TPA) increases noticeably for excitation to the higher excited states. The photophysical properties of benzannelated enediynes are sensitive to substitutions at both the core and the periphery of the enediyne chromophore. Considerably enhanced two-photon absorption is observed in an enediyne with donor substitution in the middle and acceptor substitution at the termini. Excited states with B symmetry are not active in TPA spectra. From a practical point of view, this study extends the range of wavelengths applicable for activation of the enediyne moiety from 350 to 600 nm and provides a rational basis for future studies in this field. Our theoretical computations confirmed that lowest energy TPA in benzannelated enediynes involves different orbitals than lowest energy one-photon absorbance and provided further support to the notion that introduction of donor and acceptor substituents at different ends of a molecule increases TPA.     

Trinitroethyl ethers of substituted alcohols

The influence of the trinitromethane salt cations and the substituents in the alkyl moiety of chloromethyl ethers of alcohols on the yields of trinitroethyl ethers of the substituted alcohols formed from them was established. On this basis a representative series of previously unavailable trinitroethanol ethers was synthesized.