Stannous chloride mediated one pot synthesis of functionalized indole-3-yl pyridines using 3-cyanoacetylindoles and 3-formylchromones

An efficient one-pot synthesis of functionalized indole-3-yl pyridines by condensation of 3-formylchromones, cyanoacetylindoles and ammonium acetate has been achieved. A series of 17 new compounds were synthesized and all of them were characterized by FT-IR and NMR. The crystal structure of a typical compound was determined by X-ray diffraction. A variety of substrates can participate in the process resulting in high purity and good yields, making this methodology suitable for library synthesis in drug discovery.     

Heteroarenium salts in synthesis. Highly functionalized tetra- and pentasubstituted pyridines

Activation of chloropyridines by heteroarenium substituents allows sequential substitutions by O-, N-, and S-nucleophiles. Reaction of 2,3,5,6-tetrachloropyridine and 4-ethylsulfanyl-2,3,5,6-tetrachloropyridine with 4-(dimethylamino)pyridine, 4-(pyrrolidin-1-yl)pyridine, or 4-aminopyridine results in the formation of 2,6-bis-heteroarenium substituted 3,5-dichloropyridines. On nucleophilic displacement of the heteroarenium substituents by O-, N-, or S-nucleophiles highly functionalized 3,5-dichloropyridines form which possess N²,S⁴,N⁶-, O²,S⁴,O⁶-, O²,O⁶-, N²,N⁶-, and S²,S⁶-substitution patterns.     

Synthesis of 2,2′-bipyrrole-5-carboxaldehydes and their application in the synthesis of B-ring functionalized prodiginines and tambjamines

Facile, versatile, and cost-effective synthetic routes for the preparation of a range of new 3-alkyl-, 4-alkyl-, 3,4-dialkyl-, and 3-halo-4-alkyl-2,2′-bipyrrole-5-carboxaldehydes have been developed. These 2,2′-bipyrrole-5-carboxaldehydes offer interesting potential as building blocks for making bioactive natural and unnatural products, as demonstrated by the synthesis of B-ring functionalized prodiginines (PGs) and tambjamines.     

Synthesis of mesomorphic 2-alkyl-5-(p-cyanophenyl)pyridines

A new series of liquid-crystal derivatives of 2-alkyl-5-(p-cyanophenyl)pyridines were obtained by halogenation of 2-alkyl-5-phenylpyridines under the conditions of the Birckenbach-Gubo-Waters reaction with subsequent conversion of the 2-alkyl-5-(p-bromo- or iodophenyl) pyridines to the cyano derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 85–88, January, 1981.     

A new synthesis of 2-substituted pyridines via aluminum chloride induced heteroarylation of arenes and heteroarenes

[reaction: see text] We herein report a new synthesis of 2-(hetero)aryl-substituted pyridines via heteroarylation of arenes/heteroarenes through AlCl(3)-induced C-C bond-forming reactions. 2-Halopyridines bearing an electron-withdrawing group were reacted with a number of (hetero)arenes to give 2-aryl/heteroaryl-substituted pyridines in good yields.     

Highly efficient synthesis of functionalized indolizines and indolizinones by copper-catalyzed cycloisomerizations of propargylic pyridines

The copper-catalyzed cycloisomerizations of 2-pyridyl-substituted propargylic acetates and its derivatives are described, which offer an efficient route to C-1 oxygenated indolizines with a wide range of substituents under mild reaction conditions. The presented method could be readily applied to the synthesis of indolizinones through a cyclization/1,2-migration of tertiary propargylic alcohols.     

Scope of a novel three-component synthesis of highly functionalized pyridines(dagger)

A mechanistically unique three-component synthesis provides a variety of functionalized pyridine derivatives in fair to excellent yields. The scope of this reaction was studied with respect to the alkoxyallene, the nitrile, and the carboxylic acid. Due to the 4-hydroxy group, these pyridine derivatives are suitable precursors for subsequent palladium-catalyzed reactions. Suzuki couplings of the corresponding pyridyl nonaflates lead to a variety of pyridine and bipyridine derivatives.     

Synthesis of 5-n-alkyl-2-(trans-4-n-alkylcyclohexyl)pyridines

The cyclization of trans-1-acrylyl-4-n-alkylcyclohexanes with trans-1-N-piperidino-1-alkenes was used to synthesize 3-n-alkyl-6-(trans-4-n-alkyl-cyclohexyl)-3,4-dihydro-2-N-piperidino-2H-pyrans, which were converted under the influence of hydroxylamine to 5-n-alkyl-2-(trans-4-n-alkylcyclohexyl)-pyridines. Problems in the stereochemistry of the cyclohexane derivatives in the investigated scheme of synthesis were examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–647, May, 1984.     

Substituted pyridines. 2, 5-Dimethyl-4-p-nitrobenzylpyridine and its reactions

2, 5-Dimethyl-4-p-nitrobenzylpyridine has been prepared. Its nitro group has been reduced and its methylene group oxidized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp 1225–1227, September, 1970.     

Synthesis of 5H-1, 2-dihydro-2, 5-dioxochromeno [2,3-b] pyridines

Some representative 5H-1,2-dihydro-2,5-dioxochromeno[2,3-b]pyridines have been prepared by condensation of 2-isocyanatochromone (obtained by Curtius rearrangement of the azide of chromone-2-carboxylic acid) with enamines, followed by cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 588–589, May, 1970.     

Synthesis of a novel poly(ethylene glycol) grafted triethylamine functionalized dicationic ionic liquid and its application in one-pot synthesis of 2-amino-2-chromene derivatives in water

A novel poly(ethylene glycol) grafted triethylamine functionalized dicationic ionic liquid has been prepared and characterized. It was successfully used as an efficient catalyst for the three-component synthesis of 2-amino-2-chromene derivatives in water. The simple workup, mild reaction conditions, wide substrate flexibility, excellent yields, and environmental friendliness are notable advantages of this protocol. In addition, the catalyst could be reused several times without appreciable reduction of catalytic activity.     

Ammonium chloride catalyzed one-pot synthesis of imidazo[1,2-a]pyridines

Ammonium chloride as a very inexpensive and readily available reagent efficiently catalyzes one-pot, three-component Groebke condensation reactions of aldehydes, isocyanides, and 2-aminopyridines or 2-aminopyrimidines in methanol to afford the corresponding imidazo[1,2-a]pyridines in high yields at room temperature. Correspondence: Ahmad Shaabani, Department of Chemistry, Shahid Beheshti University, PO Box 19396-4716, Tehran, Iran.     

Synthesis of differentially protected cyclopentitol: its application towards the stereoselective synthesis of 5-epi-calditol

The synthesis of differentially protected cyclopentitol derivative 5 is described using ring-closing metathesis of a diene derived from d-mannose. Subsequent chemical modifications such as catalytic osmylation and chain extension using glycidyl triflate completed the synthesis of 5-epi-calditol.     

One-pot synthesis of highly functionalized pyridines via a rhodium carbenoid induced ring expansion of isoxazoles

A concise one-pot synthesis of highly functionalized pyridines has been developed. The first step in the reaction sequence is the formal insertion of rhodium vinylcarbenoids across the N-O bond of isoxazoles. Upon heating, the insertion products undergo a rearrangement to give 1,4-dihydropyridines. DDQ oxidation then affords the corresponding pyridines in 31-84% yield. The process has proven general with a range of carbenoid and isoxazole components and represents a unique disconnection strategy for the synthesis of functionalized pyridines.     

Preparation of chiral, highly functionalized cyclopentanes and its application to the synthesis of prostaglandin E1

This paper describes the preparation of the polyfunctionalized cyclopentane ((+/-)-5) by silica gel-catalyzed air-oxidation, and its kinetic resolution by means of microbial reduction with Rhodotorula rubra to afford optically pure (-)-5 (greater than 99% ee). Starting with (-)-5, a new route to prostaglandin E1 was established.     

Synthesis of water-tolerant indium homoenolate in aqueous media and its application in the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling with acid chloride

The first water-tolerant, ketone-type indium homoenolate was synthesized via the oxidative addition of In/InCl(3) to enones. The reaction proceeds exclusively in aqueous media. Both indium and indium(III) chloride are necessary for the smooth conversion of the reaction. Similar results were obtained when InCl or InCl(2) was used in place of In/InCl(3). The synthetic utility of the indium homoenolate was demonstrated through the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling of indium homoenolate with acid chloride.     

A metathesis-based approach to the synthesis of 2-pyridones and pyridines

The ring-closing metathesis reaction has been successfully employed to form a range of dihydropyridone intermediates, which are in the correct oxidation state to undergo a base-induced elimination to reveal the aromatic 2-pyridone. This mild and novel approach to six-membered heteroaromatic compounds then provides access to a wide variety of substituted pyridines in excellent overall yield.     

3-[Amino(methylthio)methylene]pentane-2,4-dione in the synthesis of functionalized pyridines

New syntheses of functionalized pyridines from 3-[amino(methylthio)methylene]-2,4-pentanedionevia its boron chelates were proposed. The products of condensation of dimethylformamide dimethylacetal with the latter chelates were converted into 3-acetyl-2-methylthio-4-hydroxypyridine by refluxing in BuOH and into 1-alkyl-3-cyano-2-methyl-4-pyridones by treatment with primary amines.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1118–1121, June, 1995.This study was financially supported by the International Science Foundation (Grant M5Q 000).