Selective synthesis of di(propen-1-yl)sulfone and di(propen-1-yl)sulfoxide

Convenient selective methods of synthesis of the title compounds, based on oxidation of di(propen-1-yl)sulfide with 30% H₂O₂, have been developed.Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 675–679, March, 1992.     

One-pot synthesis of 3-(pyridin-2-yl)-2,3-dihydroazetes via Rh(II)-catalyzed reaction of diazoesters with trimethylsilyl-protected 2-(pyridin-2-yl)-2H-azirines

Chemistry of Heterocyclic Compounds - A one-pot method for the synthesis of 3-(pyridin-2-yl)-2,3-dihydroazetes was developed on the basis of Rh2(esp)2-catalyzed reaction of diazoesters with...     

4-Arylvinyl-2,6-di(pyridin-2-yl)pyrimidines: synthesis and optical properties

A series of 4-arylvinyl-2,6-di(pyridin-2-yl)pyrimidines have been efficiently prepared by a double cross-coupling reaction between 2,4-dichloro-6-methylpyrimidine and 2-(tributylstannyl)pyridine, followed by aldol condensation with the appropriate aromatic aldehyde substituted with electron-donating, electron-withdrawing, dendritic, or water-soluble groups. The effect of different protic and aprotic solvents on the optical absorption and emission properties of these systems was studied. Compounds with electron-donating groups display strong emission solvatochromism, suggesting the formation of an intramolecular charge-separated emitting state. The solvatochromic behavior depends not only on the solvent polarity but also on the hydrogen bonding parameters of the solvent. The effect of protonation was also studied, and the abilities of some of these molecules to function as colorimetric and luminescent pH sensors were demonstrated with dramatic color changes and luminescence switching upon the introduction of acid.     

Oxidative condensation reactions of (diethylenetriamine)cobalt(III) complexes with substituted bis(pyridin-2-yl)methane ligands

The synthesis and characterisation of Co(III) complexes derived from a condensation reaction with a central or terminal nitrogen of a dien ligand and the -carbon of a range of substituted bis(pyridin-2-yl)methane ligands are described. Aerial oxidation of bpm {bis(pyridin-2-yl)methane with Co(II)/dien or direct reaction with Co(dien)Cl₃ provided in low yield a single C–N condensation product 1 (at the primary terminal NH₂) after the pyridyl –CH₂– is formally oxidised to –CH⁺–. The methyl substituted ligand bpe {1,1-bis(pyridin-2-yl)ethane} behaves likewise, except both terminal (prim) and central (sec) amines condense to yield isomeric products 2 and 3. Two of these three materials have been characterised by single crystal X-ray crystallography. The corresponding reactions for the bis(pyridyl) ligand bpk {bis(pyridin-2-yl)ketone} provided C–N condensation products without the requirement for oxidation at the -C center; two carbinolamine complexes in different geometrical configurations resulted, mer-anti-[Co(dienbpc)Cl]ZnCl₄, 5, and unsym-fac-[Co(dienbpc)Cl]ZnCl₄, 6, {dienbpc=[2-(2-aminoethylamino)-ethylamino]-di-pyridin-2-yl-methanol}. In addition, a novel complex, [Co(bpk)(bpd-OH)Cl]ZnCl₄, 4, in which one bidentate N, N-bonded bpk ligand and one tridentate N, O, N-bonded bpd (the diol from bpk+OH⁻) were coordinated, was obtained via the Co(II)/O₂ synthetic route. When the bpc ligand (bpc=bis(pyridin-2-yl)methanol) was employed directly as a reagent along with dien, no condensation reactions were observed, but rather a single isomeric complex [Co(dien)(bpc)]Cl.ZnCl₄, 7, in which the ligand bpc acted as a N,N,O-bonded tridentate ligand rather than as a N,N-bidentate ligand was isolated. ¹³C, 1D and 2D ¹H NMR studies are reported for all the complexes; they establish the structures unambiguously.     

Synthese und reaktionen von di(benzthiazol-2-yl)- und di(benzoxazol-2-yl)methylgerman

Reaction of benzthiazol-2-yl and benzoxazol-2-yl-trimethylstannane with methyltrichlorogermane leads to the mono-, bis- and tris-heterocyclic substituted germanes RGe(Me)Cl₂, R₂Ge(Me)Cl, R₃GeMe (2, 3, 4: R = benzthiazol-2-yl; 6, 7, 8: R = benzoxazol-2-yl), which exist in a mobile equilibrium. From the chlorogermanes 2, 3 and 6, 7 the corresponding germanes 9, 10 and 11, 12 can be obtained by reaction with trimethylstannane. From the germane 10 the mono- and bis-N-methylated salts 15 and 17 can be synthesized. The compounds 10, 12 and 15 easily decompose by α-elimination reactions. The salt 17 can be regarded as a suitable model substance for the synthesis of a germacyanine dye.     

4-(pyridin-2-yl)thiazol-2-yl thioglycosides as bidentate ligands for oligosaccharide synthesis via temporary deactivation

This study focusses on a new concept for oligosaccharide synthesis based on 4-(pyridin-2-yl)thiazol-2-yl thioglycosides that can either act as effective glycosyl donors or can be deactivated by stable bidentate complexation with palladium(II) bromide.     

Metal-free synthesis of pyridin-2-yl ureas from 2-aminopyridinium salts

An unprecedented base promoted domino approach has been developed for the synthesis of pyridin-2-yl urea derivatives via the reaction of 2-aminopyridinium salts and arylamines. The developed strategy tolerated a wide range of functional groups and afforded pyridin-2-yl ureas in moderate to good yields. The reaction was postulated to involve tandem cyclization, intermolecular nucleophilic addition, ring opening, and demethylation.     

Synthesis of symmetrical di(pyrimidin-2-yl)-1,2,4-triazoles and di(pyrimidin-2-yl)-1,2,4,5-tetrazines

The reactions of pyrimidine-2-carbonitrile and 4,6-dimethylpyrimidine-2-carbonitrile with hydrazine hydrate were investigated. Intermediates in the route of successive transformations of pyrimidine-2-carbonitrile (pyrimidine-2-carbamidrazone and 1,2-bis[amino(pyrimidin-2-yl)methylidene]hydrazine) into trinuclear heterocyclic compounds, viz., symmetrical di(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazines and di(pyrimidin-2-yl)-4H-1,2,4-triazol-4-amines (potential polydentate ligands), were isolated. The oxidative dehydrogenation of di(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazines afforded the corresponding 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazines.     

Di(4,5,6,7-tetrafluorobenzothiazol-2-yl) disulfide: synthesis and reactions with amines

Di(4,5,6,7-tetrafluorobenzothiazol-2-yl) disulfide, obtained by oxidation of 2-mercapto-4,5,6,7-tetrafluorobenzothiazole, readily reacts with aliphatic and alicyclic amines to form the corresponding sulfenyl amides. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1225–1226, June, 2007.     

Microwave-assisted synthesis of 3,6-di(pyridin-2-yl)pyridazines: unexpected ketone and aldehyde cycloadditions

3,6-Di(pyridin-2-yl)pyridazines are an interesting class of compounds because of their metal-coordinating ability resulting in the self-assembly into [2x2] gridlike metal complexes with copper(I) or silver(I) ions. These and other substituted pyridazines can be prepared by the inverse-electron-demand Diels-Alder reactions between acetylenes and 1,2,4,5-tetrazines. In this contribution, the effect of (superheated) microwave conditions on these generally slow cycloadditions is described. The cycloaddition of acetylenes to 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine could be accelerated from several days reflux in toluene or N,N-dimethylformamide to several hours in dichloromethane at 150 degrees C. In addition, the unexpected cycloaddition of the enol tautomers of various ketones and aldehydes to 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine is described in detail providing an alternative route for the synthesis of (substituted) pyridazines.     

Formation and crystal structures of [(alkoxy)bis(pyridin-2-yl)methanolato-N,O,N]tin(IV) complexes

Reactions of bis(pyridin-2-yl)ketone with tin tetrahalides, SnX₄ (X = Cl or Br), or organotin trichlorides, R^′SnCl₃ (R^′ = Ph, Bu or CH₂CH₂CO₂Me), in ROH (R = Me or Et) readily produces RObis(pyridin-2-yl)methanolato)tin complexes, [5: RO(py)₂C(OSnX₃)] (5: R,X = Me,Cl; Et,Cl; Et,Br) or [6: MeO(py)₂C(OSnCl₂R^′)] (R^′ = Ph, Bu, CH₂CH₂CO₂Me). In addition, halide exchange reaction between SnI₄ and (5: R,X = Me,Cl) occurred to give (5: R,X = Me,I). The crystal structures of six tin(IV) derivatives indicated, in all cases, a monoanionic tridentate ligand, [RO(py)₂C(O⁻)-N,O,N], arranged in a fac manner about a distorted octahedral tin atom. The Sn–O and Sn–N bonds lengths do not show much variation amongst the six complexes despite the differences in the other ligands at tin.     

Efficient synthesis of 4-phosphinoyl-4,5,6,7-tetrahydro-2H-indazol-3-ylamines

We described in this paper an efficient synthesis of variously substituted 4-phosphinoyl-4,5,6,7-tetrahydro-2H-indazol-3-ylamines involving nucleophilic addition of hydrazine on β-ketothioamides as key-step.     

Parallel solution-phase synthesis of substituted 2-(1,2,4-triazol-3-yl)benzimidazoles

A solution-phase synthesis for the preparation of substituted 2-(1,2,4-triazol-3-yl)benzimidazoles from triazole aldehydes and ortho-phenylenediamines has been developed for the purpose of producing diverse lead generation libraries. Crude products were obtained and further purified by mass-guided preparative HPLC.     

Efficient one-pot synthesis of highly substituted pyridin-2(1H)-ones via the Vilsmeier-Haack reaction of 1-acetyl,1-carbamoyl cyclopropanes

A facile and efficient one-pot synthesis of highly substituted pyridin-2(1H)-ones is developed via the Vilsmeier-Haack reaction of readily available 1-acetyl,1-carbamoyl cyclopropanes, and a mechanism involving sequential ring-opening, haloformylation, and intramolecular nucleophilic cyclization reactions is proposed.     

SnCl2-catalyzed selective atom economic imino Diels-Alder reaction: synthesis of 2-(1H-pyrrolo[2,3-b]pyridin-3-yl)quinolines

The synthesis of 2-(1H-pyrrolo[2,3-b]pyridin-3-yl)quinolines by a SnCl(2)-catalyzed multicomponent reaction has been described. The reaction proceeds chemo- and regioselectively in an atom-economic way, generating a library of 24 quinoline derivatives.     

Chemistry of 3-Oxo-N-(pyridin-2-yl)butanamide and Related Compounds

This review highlights the methods used for the synthesis of 3-oxo-N-(pyridin-2-yl)butanamide compounds. The reactivity and synthetic importance are investigated. In this context, recent progress in the synthesis and use of 3-oxo-N-(pyridin-2-yl)butanamide as precursors for heterocyclic compounds is reviewed. The synthetic routes for preparation of 3-oxo-N-(pyridin-2-yl)butanamide are based on the reaction of diketene with aromatic primary amine and reaction of 2-aminopyridine with β-keto-t-butylthioester or ethylacetoacetate. The bibliography includes 73 references.     

Highly enantioselective nitroaldol reactions catalyzed by copper(II) complexes derived from substituted 2-(pyridin-2-yl)imidazolidin-4-one ligands

Ten optically pure substituted 2-(pyridin-2-yl)imidazolidin-4-ones, 1a-d, 2a-4a, and 2b-4b, were prepared and characterized. The absolute configurations of individual ligands were determined by X-ray analysis or NOESY experiments. The Cu(II) complexes of the respective ligands were studied as enantioselective catalysts of the nitroaldol (Henry) reaction of aldehydes with nitromethane, giving the corresponding substituted 2-nitroalkanols. In the case of an anti arrangement of the imidazolidin-4-one ring, the obtained result was 91-96% ee, whereas in the case of syn arrangement, a significant drop to 25-27% ee was observed.     

Direct synthesis of guanidines using di(imidazole-1-yl)methanimine

A direct synthetic approach to guanidine compounds is reported here using di(imidazole-1-yl)methanimine and di(imidazole-1-yl)cyanomethanimine as guanylating reagents.     

An improved amide coupling procedure for the synthesis of N-(pyridin-2-yl)amides

Dehydrative amide couplings with 2-pyridylamines suffer from variable yields. A mild and high-yielding synthesis of N-(pyridin-2-yl)amides employing 2-aminopyridine-N-oxides is presented as a solution.