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.     

Interaction of benzothieno[2,3-c]pyrylium salts with hydrazine. Derivatives of 5H-[2,3]benzothieno[2,3-e]diazepines

A study has been made of the reaction of 1,3-disubstituted bezothieno[2,3-c]pyrylium salts with hydrazine. It has been shown that 1,3-dialkyl-substituted benzothieno[2,3-c]pyrylium salts interact with hydrazine to give N-amino-1,3-dialkylbenzothieno[2,3-c]pyridines. The presence of a pyrylium ring on one of the positions of the phenyl group leads to a mixture of N-amino derivatives and 5H-[2,3]benzothieno[2,3-e]diazepines. In contrast, 1,3-diphenylbenzothieno[2,3-c]pyrylium perchlorate gives exclusively 5H-[2,3]benzothieno[2,3-e]diazepine.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Tar Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translate from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp 1137–1140, August, 1998.     

Identification of 2,3-dimethyl-2,3-diisobutyl succinonitrile in laser printer emissions

2,3-Dimethyl-2,3-diisobutyl succinonitrile was identified as the main volatile organic compound (>90%) emitted from laser printers during the printing process. Experiments were carried out in a large environmental chamber of 30 m3, where the printers were placed and working simulating 'real office setting' conditions. Air samples were taken on Tenax TA adsorbent cartridges in the vicinity of the printers and further analyzed by thermal desorption gas chromatography/mass spectrometry (TDGC/MS). The structure of the compound has been determined and is presented in this study. Additional data obtained by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and liquid chromatography/tandem mass spectrometry (LC/MS/MS) support the proposed structure, with no reported CAS number, as 2,3-dimethyl-2,3-diisobutyl succinonitrile. It is a byproduct of the thermal decomposition of 2,2'-azobis(2,4-dimethyl valeronitrile), a commercially available free radical polymerization initiator used in polymerization processes during the manufacture of the toners. By means of head-space GC/MS, 15 toners used in black & white and colour printers have been investigated. Six of them contained 2,3-dimethyl-2,3-diisobutyl succinonitrile, which has also been detected in the respective processed paper.     

A Practical 2,3-Pyridyne Precursor

3-Bromo-2-chloro-4-methoxypyridine has been developed as a practical 2,3-pyridyne precursor. The substituted 2,3-pyridyne generated from this precursor by halogen-metal exchange has been found to react regioselectively with 2-methoxyfuran and 2-methylfuran.     

2,3-Benzodiazepine-1-thione in the synthesis of substituted and hetero-annelated 2,3-benzodiazepines

A series of S-substituted and 1,2-annelated derivatives of 2,3-benzodiazepine has been obtained on the basis of 2,3-benzodiazepine-1-thione. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 594-601, April, 2009.     

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.     

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.     

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.     

Synthesis of 2-substituted-2,3- dihydro-1,4-dioxino[2,3-b]pyridine derivatives

[reaction--see text] A variety of 2-substituted-2,3-dihydro-1,4-dioxino[2,3-b]pyridines B have been synthesized from the readily available 2-nitro-3-oxiranylmethoxypyridine 1 via a Smiles rearrangement. We demonstrate how variations of reaction conditions affect the product distribution of A and B.     

Synthesis and stereochemistry of trans- and cis-2,3-difluoro-2,3-dihydrobenzofuran

The geometrical isomers of 2,3-difluoro-2,3-dihydrobenzofuran have been prepared and their structure assigned on the basis of the nmr spectra. Some suggestions on the conformational situation of two adducts are also reported.     

Preparation and characterization of 2,3-dihydro-2,3 bis (methylene) furan

2,3-dihydro-2,3 bis (methylene) furan and its 4-methyl derivative have been prepared by flash vacuum thermolysis and characterized by mass spectrometry and chemical trapping.     

Five-membered 2,3-dioxoheterocycles. 28. Reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with thioamides and thiosemicarbazides

The reaction of 5-aryl-2,3-dihydrofuran-2,3-diones (I) with thiocarbonyl compounds has been described only for thiourea. The products of this reaction are 3-aryl-5-phenacylidene-4-oxoimidazolidine-2-thiones [2]. It seemed of interest to study the conversion of the furandiones (I) with a wider range of thiocarbonyl compounds such as thioamides and thiosemicarbazides.For Communication 27 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1461–1464, November, 1992.     

Asymmetric hydrogenation catalyzed by rhodium complexes of 2,3-bis(dimenthylphosphino)maleic anhydride and 2,3-bis(dimenthylphosphino)-N-phenylmaleimide

2,3-Bis(dimenthylphosphino)maleic anhydride and the phenylimide derivative have been prepared from 2,3-dichloromaleic anhydride and 2,3-dichloro-N-phenylmaleimide, respectively, and dimenthyl(trimethylsilyl)phosphine. These compounds have been used as ligands for Rh complexes and have been tested in the asymmetric hydrogenation of α-acetamidocinnamic acid, methyl-α-acetamidocinnamate and itaconic acid. Optical yields of up to approximately 70% were obtained with α-acetamidocinnamic acid.     

One-pot synthesis of 2,3-dihydro-1H-benzimidazoles

A convenient one-pot method for the synthesis of 2,3-dihydro-1H-benzimidazoles has been elaborated. A set of 2,3-dihydro-1H-benzimidazoles was prepared from various ortho-dialkylaminoanilines and aldehydes using Me3SiCl as a condensation agent and pyridine as a basic medium.     

Stereocontrolled Organocatalytic Strategy for the Synthesis of Optically Active 2,3‐Disubstituted cis‐2,3‐Dihydrobenzofurans

An intramolecular, organocatalyzed Michael addition has been developed to obtain biologically important 2,3‐disubstituted cis‐2,3‐dihydrobenzofurans. By using mandelic acid salts of primary aminocatalysts, derived from cinchona alkaloids, the intramolecular cyclization reaction has been developed to proceed in high yield, with moderate to good diastereoselectivity, and up to 99 % ee. Based on the absolute configuration of the formed 2,3‐disubstituted‐cis‐2,3‐dihydrobenzofurans and by considering the observed substrate scope restrictions, a mechanistic rationalization has been presented.     

Bisallyl and bismethallyl derivatives of 2,3-dihydroxypyridine

2,3-Dihyroxypyridine has been dialkylated with allyl bromide and methallyl chloride to give 1-allyl-3-allyloxy-2-pyridone ( 2 ) and 1-methallyl-3-methallyloxy-2-pyridone ( 3 ), respectively. These compounds readily undergo a Claisen rearrangement at 163° to give the bis-1,4-allyl-3-hydroxy-2-pyridone isomers, 4 and 5 , respectively. 2,3-Bisallyloxypyridine ( 8 ) and 2,3-bismethallyloxypyridine ( 9 ) were synthesized from 2-chloro-3-hydroxypyridine.     

Five-membered 2,3-dioxoheterocycles

The reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with benzamide oxime, diaminoglyoxime, and hydroxyurea gave 3-phenyl-5-aroylacetyl-1,2,4-oxadiazoles, 5,6-dihydroxyimino-3-phenacylidenepiperazin-2-ones, and 3-hydroxy-5-phenacylideneimidazolidine-2,4-diones, respectively. 6-Phenacylidene-5-oxo-4,5,6,7-tetrahydrofurazano [3,4-b]pyrazines are formed in the reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with diaminofurazan.For Communication 7, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1457–1460, November, 1988.     

Polysubstituted 2,3-dihydrofuro[2,3-b]pyridines and 3,4-dihydro-2H-pyrano[2,3-b]pyridines via microwave-activated inverse electron demand Diels-Alder reactions

Polysubstituted 2,3-dihydrofuro[2,3-b]pyridines and 3,4-dihydro-2H-pyrano[2,3-b]pyridines have been synthesized from 1,2,4-triazines using the inverse electron Diels-Alder reaction. For this purpose, 3-methylsulfanyl-1,2,4-triazines were reacted with several nucleophiles allowing the formation of appropriately substituted alkynes to undergo the intramolecular inverse electron demand Diels-Alder reaction. Sealed-tube microwave activation of the cycloaddition reaction has proved to be very efficient and allowed shorter reaction times. This strategy enabled an efficient synthesis of 3-hydroxy-2,3-dihydrofuro[2,3-b]pyridines and 4-hydroxy-3,4-dihydro-2H-pyrano[2,3-b]pyridines with several points of diversity on the bicyclic scaffold.     

One-pot approach to 2,3-disubstituted-2,3-dihydro-4-quinolones from 2-alkynylbenzamides

Concise and efficient syntheses of various trans-2,3-disubstituted-2,3-dihydro-4-quinolones have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides, nucleophilic addition of alcohols to the isocyanate intermediates, intermolecular [2+2]-cycloaddition with carbon-carbon triple bonds and aldehydes, and intramolecular aminocyclization of nitrogen of carbamates to the α,β-unsaturated ketones.     

Synthesis of functionalized 2,3-dihydroisoxazoles by domino reactions in water and unexpected ring-opening reactions of 2,3-dihydroisoxazoles

α,α-Dicyanoolefins react with hydroxylamine to afford 2,3-dihydroisoxazoles (2,3-dihydroisoxazoles can be easily isolated by filtration) in excellent yields under mild and environmentally benign conditions. A one-pot reaction in tandem with an unexpected ring-opening of 2,3-dihydroisoxazoles has been developed as well.