Synthesis and cyclization of 1-arylalk-1-ene-3,5-diynylamines

An investigation of the reaction of 1-lithio-1,3-diynes, generated in situ, with nitriles has been carried out. In the case of aromatic nitriles 1-arylalk-1-ene-3,5-diynylamines are formed, which undergo dimerization and cyclization on isolation, giving 3-(alka-1,3-diynyl)-4-(alk-2-ynyl)-2,6-diarylpyridines. The effect of the nature of the substituent in the benzonitrile molecule on the selectivity of the reaction and the yield of the products has been determined. A scheme is proposed for the conversions and the structures of the intermediates have been established. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 701–710, May, 2006.     

Synthesis,X-ray and DFT Studies of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones

Chemistry of Heterocyclic Compounds - The Richter cyclization was used for the synthesis of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones. X-ray analysis revealed that these compounds exist as dimers...     

Chiral acyclic diaminocarbene complexes of palladium(II) immobilized on a polymeric support as promising catalysts of the Suzuki reaction

Metal-promoted nucleophilic addition of primary amino group of a natural L-amino acid anchored on polystyrene support to coordinated isonitrile substrate has afforded preparation and simultaneous immobilization of chiral acyclic diaminocarbene complex of palladium(II). The obtained catalytic system is stable under conditions of the Suzuki reaction and demonstrates good catalytic activity in the reaction with a sterically hindered substrate.     

Dipolar cycloaddition of N-aryl-C-(2,2-dichloro-1-phenylcyclopropyl)nitrones to N-arylmaleimides

1,3-Dipolar cycloaddition of N-aryl-C-(2,2-dichloro-1-phenylcyclopropyl)nitrones to N-arylmaleimides stereoselectively gives substituted pyrrolo[3,4-d]isoxazolidines as mixtures of two diastereoisomers differing by configuration at the C^1′ atom of the cyclopropane ring in the substituent on C³. Substituents in the aromatic rings of the initial nitrone and maleimide do not affect the stereochemistry of the process.     

“Acetylene Zipper” Reactions and Pd-Cu-Catalyzed Cross-coupling in the Synthesis of Vicinal 1,3-Alkadiynylarylamines and Aminopyridines

A preparative method was developed for vicinal-substituted 1,3-alkadiynylarylamines and aminopyridines involving a successive application of acetylene zipper reaction to synthesize 1,3-alkadiynes followed by Sonogashira reaction.     

Study of cyclyzation of o-(1-Alkynyl)- and o-(1,3-Butadiynyl)aryltriazenes under the action of acids

The investigation of Richter cyclization of o-(1-alkynyl)- and o-(1,3-butadiynyl)arenediazonium salts generated by acid cleavage of triazenes was carried out by the methods of NMR and ESI MS (Electrospray Ionization Mass Spectrometry). The effect was shown of the substituents at the carbon atom of the triple bond and in the aromatic ring, of the solvent, temperature, and the reagents ratio on the rate of the cyclization and the yield of its products, 4-bromo-3-alkyl- and 4-bromo-3-ethynylcinnolines; the conditions of their synthesis were optimized. The possibility to use 4-bromo-3-ethynylcinnolines as substrates of electrophilic cyclization was demonstrated.     

Studies on cyclization of o-(alka-1,3-diynyl)arenediazonium salts

The Richter reaction of o-(alka-1,3-diynyl)arenediazonium salts, obtained by diazotization of diacetylenic derivatives of anilines, leads to 3-alkynyl-4-chloro- or 3-alkynyl-4-bromocinnolines and/or 3-alkynyl-4-hydroxycinnolines (the latter cyclize into furo[3,2-c]-cinnolines under the reaction conditions). 3-Alkynyl-4-chlorocinnolines undergo solvolysis in methanol giving rise to 3-alkynyl-4-methoxycinnolines, the subsequent hydrolysis of which also gives furo[3,2-c]cinnolines. Effects of the nature of substituents in the aromatic ring and of the reaction conditions on the product composition and yields have been established. The reaction course has been studied by spectrophotometry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1693–1700, August, 2008.     

Catalytic activity of palladium(II) diaminocarbene complexes in the Sonogashira and Suzuki reactions

Palladium(II) complexes with chelating and non-chelating diaminocarbene ligands were assessed as catalysts in the cross-coupling reactions of haloarenes with oct-1-yne (Sonogashira reaction) and phenylboronic acid (Suzuki reaction). Both complexes exhibited a higher catalytic activity than traditional phosphine ligandbased systems in the Sonogashira reaction, and they ensured cross-coupling not only with iodoarenes but also with bromoarenes activated by electron-withdrawing substituents. The catalytic activities of the examined complexes in the Suzuki reaction were appreciably different: the palladium(II) complex with the chelating ligand turned out to be considerably less active than the complex with the non-chelating ligand.