Boric acid catalyzed convenient synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines in aqueous media

A one-pot three-component condensation of an aldehyde, malononitrile, and thiophenol has been achieved by conventional and ultrasound method. The reaction has been catalyzed by boric acid in aqueous medium. This protocol afforded corresponding 2-amino-3,5-dicarbonitrile-6-thio-pyridines in shorter reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents.     

Novel ZnCl2-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines

ZnCl₂-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines under microwave heating and conventional heating is described.     

2-Hydroxyethylammonium acetate: A reusable task-specific ionic liquid promoting one-pot,three-component synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines

2-Hydroxyethylammonium acetate (2-HEAA) as a task-specific ionic liquid, efficiently promotes one-pot three-component reaction of aryl/heteroaryl/alkyl aldehydes with aryl/alkyl thiols and malononitrile at room temperature. This protocol offers several advantages such as using a reusable and cost-effective ionic liquid, being amenable to scale-up and produces the corresponding 2-amino-3,5-dicarbonitrile-6-thio-pyridines in a short reaction time (5 min) and in good to high yields.     

An efficient synthesis of 2-amino-4-aryl-3,5-dicarbonitrile-6-ethoxypyridine derivatives by the solvent taking part in the reaction

An efficient and facile synthesis of 2-amino-4-aryl-3,5-dicarbonitrile-6-ethoxypyridine via reaction of aromatic aldehydes, malononitrile, and ethanol in the presence of NaOH has been developed, without using the classic reagents amines and 1,3-dicarbonyl compounds. It is interesting that weak nucleophilic reagent ethanol could take part in the reaction without using strong base catalyst sodium ethylate. Compared with existing methods, the reported process has the advantages of excellent yields, easily obtainable raw materials, and mild reaction conditions.     

A simple,economical, and environmentally benign protocol for the synthesis of 2-amino-3,5-dicarbonitrile-6-sulfanylpyridines at ambient temperature

A simple, economical, and environmentally benign protocol has been described for one-pot synthesis of medicinally privileged 2-amino-3,5-dicarbonitrile-6-sulfanylpyridines by three-component condensation between aldehyde, malononitrile, and thiol using diethylamine as a catalyst. Ambient temperature and avoidance of conventional work-up as well as purification procedure qualify this cost-effective protocol for “green synthesis.”     

Synthesis and alkylation ofN-methylmorpholinium 6-amino-3,5-dicyano-4-methylpyridine-2-thiolate

The condensation of acetaldehyde with a twofold excess of cyanothioacetamide andN-methylmorpholine givesN-methylmorpholinium 6-amino-3,5-dicyano-4-methylpyridine-2-thiolate. This compound is also formed by recyclization of 2,6-diamino-3,5-dicyano-4-methyl-4H-thiopyran. From this pyridinethiolate, several substituted 2-alkylthiopyridines and 3,6-diamino-5-cyano-4-methyl-2-methoxycarbonylthieno[2,3-b]pyridine were obtained.     

Potassium phthalimide promoted green multicomponent tandem synthesis of 2-amino-4H-chromenes and 6-amino-4H-pyran-3-carboxylates

A one-pot efficient, green, practical, and environmentally friendly multicomponent synthesis of 5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromenes, ethyl-6-amino-4-aryl-5-cyano-2-methyl-4H-pyran-3-carboxylates as well as 2-amino-4-aryl-7-hydroxy-4H-chromene-3-carbonitriles via tandem the Knoevenagel-cyclocondensation has been described in the presence of a green, low-cost, mild, efficient, and commercially available potassium phthalimide as the organocatalyst. This technique is a safe and ecofriendly approach to the synthesis of different 4H-chromens and 4H-pyrans that offers many merits including short reaction times, high yields, straightforward work-up, and no use of hazardous organic solvents.     

One-Pot Synthesis of 6-Alkyl-4-amino-2-bromopyridine-3,5-dicarbonitriles

Russian Journal of Organic Chemistry - A one-pot procedure has been proposed for the synthesis of 6-alkyl-4-amino-2-bromopyridine-3,5- dicarbonitriles by reaction of malononitrile dimer with...     

K2CO3-catalyzed synthesis of 2-amino-3-cyano-4H-chromene derivatives with different substituents in water

The direct three-component condensation of resorcinol, 1-(2,4-dihydroxyphenyl)ethanone or 2,4-dihydroxybenzophenone with benzaldehydes and malononitrile to generate some novel 2-amino-3-cyano-4H-chromene derivatives has been carried out over K₂CO₃ (25 mol%) with high efficiency in water as a green solvent at 70 °C.     

Synthesis and properties ofN-methylmorpholinium 6-amino-3,5-dicyano-1,4-dihydropyridine-4-spirocyclopentane-2-thiolate

The reaction of cyclopentylidenecyanothiocetamide with cyanothioacetamide andN-methylmorpholine gaveN-methylmorpholinium 6-amino-3,5-dicyano-1,4-dihydropyridine-4-spirocyclopentane-2-thiolate, which was used in the syntheses of substituted 2-alkylthiodihydropyridines and pyrazolodihydropyridine. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1849–1851, October. 1997.     

Facile synthesis of thiochromanyl-spirooxindoles via K2CO3 catalyzed tandem sulfa-Michael/Aldol reaction

A facile method for the synthesis of thiochromanyl-spirooxindoles via sulfa-Michael/Aldol reaction of 3-ylideneoxindoles with thiosalicylaldehydes has been developed. This tandem reaction, which tolerates a wide variety of functional groups, furnished diverse substituted functional thiochromanyl-spirooxindoles in up to 90% yields with good diastereoselectivities. Furthermore, the reaction system could be promoted to gram-scale efficiently under the mild conditions.     

Multicomponent synthesis of 2-alkylthio-6-amino-3,5-dicyano-1,4-dihydropyridine-4-spirocycloalkanes. Molecular and crystal structure of 6-amino-2-(2-methylbenzylthio)-3,5-dicyano-1,4-dihydropyridine-4-spirocyclopentane

2-Alkylthio-6-amino-3,5-dicyano-1,4-dihydropyridine-4-spirocycloalkanes were synthesized via the reaction of cycloalkylidene malononitriles with cyanothioacetamide and alkyl halides. The structure of 6-amino-2-(2-methylbenzylthio)-3,5-dicyano-1,4-dihydropyridine-4-spirocyclopentane was determined by the X-ray diffraction analysis.     

Synthesis of glycerol carbonate from glycerol and dimethyl carbonate catalyzed by K2CO3/MgO

A series of M/MgO (M?=?CaO, KNO₃, KOH, K₂CO₃) catalysts were prepared by a dry impregnation method and used for synthesis of glycerol carbonate from glycerol and dimethyl carbonate. It was found that K₂CO₃/MgO was the most efficient catalyst, with a glycerol carbonate yield of approximately 99% under the conditions: DMC/glycerol molar ratio 2.5:1, catalyst/raw material weight ratio 1%, reaction time 2?h, and reaction temperature 80?°C. FTIR, BET, TEM, and XRD were used for characterization of the catalyst and showed that the active sites seemed to be K₂O formed on the K₂CO₃/MgO catalyst. Finally, a recycling experiment showed that the catalyst was relatively stable and could be reused up to four times, at least, by regeneration.     

Nanosized magnesium oxide as catalyst for the rapid and green synthesis of substituted 2-amino-2-chromenes

A nanosized magnesium oxide catalyzed three-component condensation reaction of aldehyde, malononitrile, and α-naphthol proceeded rapidly in water-PEG to afford corresponding 2-amino-2-chromenes in high yields at room temperature. The greener protocol was found to be fairly general and the catalyst was reused in subsequent reactions with consistent activity.     

Electronic absorption spectra of 2-amino-6-nitro-, 4-amino-3-bromo-and 5-amino-2-bromotoluenes

A new technique—photoacoustic spectroscopy—has been used for the first time to record the u.v.-vis spectra of three substituted toluenes, namely 2-amino-6-nitrotoluene, 4-amino-3-bromotoluene and 5-amino-2-bromotoluene. The π-π* electronic transitions analogous to the benzene first primary and secondary transitions could be detected from the PAS spectra in comparison with the u.v. solution and vapour spectra recorded by conventional methods. Detection of singlet → triplet absorptions from the PAS spectra, with significant intensity, is considered to be an important feature which transitions are in general either not observed or observed with only very weak intensity, in solution or vapour, by conventional methods. The analysis shows that a few excited state combinations observed in the u.v. PAS spectra of the molecules presently studied are well comparable with such combinations in ground state observed in the near i.r. PAS spectra.     

4-alkyl-6-amino-4-N 3,N 5-diaryl-2-thioxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxamides: I. Tandem synthesis and alkylation. Molecular and crystal structure of 6-allylsulfanyl-2-amino-4-isobutyl-N 3,N 5-di-m-tolyl-3,4-dihydropyridine-3,5-dicarboxamide

4-Alkyl-6-amino-4-N ³,N ⁵-diaryl-2-thioxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxamides were obtained via tandem synthesis involving the Knoevenagel reaction, Michael reaction and intramolecular condensation. Alkylation of the obtained dicarboxamides proceeds regioselectively at the S atom to form the corresponding thioethers. Structure of 6-allylsulfanyl-2-amino-4-isobutyl-N ³,N ⁵-di-m-tolyl-3,4-dihydropyridine-3,5-dicarboxamide was uniquely determined by XRD analysis.     

Na2CO3 catalyzed CO2 gasification of coal char and its intermediate complexes

Research on Chemical Intermediates - The catalytic effect of Na2CO3 on the CO2 gasification of Zhundong coal char was analyzed using the thermo-gravimetric analyzer. Besides, the structural...     

Synthesis of 4-Acyl-2-amino-6-(arylsulfanyl)pyridine-3,5-dicarbonitriles

Russian Journal of Organic Chemistry - The reaction of 4-acyl-2-amino-6-chloropyridine-3,5-dicarbonitriles with aromatic thiols in 1,4-dioxane in the presence of triethylamine led to the formation...     

Synthesis of 4-alkyl-6-amino-3,5-dicyano-2(1H)-pyridinethiones

Condensation of aliphatic aldehydes with cyanothioacetamide has given 4-alkyl-6-amino-3,5-dicyano-2(1H)-pyridinethiones, which have also been synthesized by recyclization of 4-alkyl-2,6-diamino-4H-thiopyrans. Substituted 2-alkylthiopyridines and thieno[2,3-b]pyridines have been prepared from the pyridinethiones. 2,6-Diamino-4-isopropyl-3,5-dicyano-4H-thiopyran and 6-amino-4-isobutyl-2-methylthio-3,5-dicyanopyridine have been studied by x-ray crystallography.T. G. Shevchenko State Teaching Institute, Lugansk 348011. A. N. Nesmeyanov Institute of Organoelemental Compounds, Moscow 117813. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1655–1663, December, 1997.