Reactions of tris(2-pyridyl)phosphines and tris(2-pyridyl)phosphine oxides with some electrophiles

Treatment of tris(2-pyridyl)phosphine or tris(2-pyridyl)phosphine oxide with electrophiles such as chlorine, bromine, deuterium chloride, or benzenediazonium chloride gave unusual coupling products, i.e., 5-chloro-, 5-bromo-, 5-deuterio-, or 5-phenylazo-2,2′-bipyridyls, respectively, as a major coupling product in each case. This is considered to be the result of electrophilic substitution on a pyridyl ring in a pentacovalent phosphorane intermediate formed in each reaction. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 439–449, 1997     

Luminescent metal complexes. 4—13C NMR spectra of the tris chelates of substituted 2,2′-bipyridyls and 1,10-phenanthrolines with ruthenium(II) and osmium(II)

¹³C Chemical shifts are reported for the ruthenium(II) tris complexes of thirteen 2,2′-bipyridyls and three 1,10-phenanthrolines and for the osmium(II) tris complexes of five 2,2′-bipyridyls. Chelation induced shifts (δ_complex – δ_ligand) are discussed in terms of models for π back-bonding. ¹³C NMR is shown to be a convenient tool for the direct observation of the geometrical isomerism of complexes formed from monosubstituted ligands.     

微波辐射促进的3-烷基取代咪唑并[1,5-a]吡啶合成

分别在常规加热和微波辐射条件下, 由双(2-吡啶甲酰)、二(2-吡啶)甲酮与脂肪醛及醋酸铵在醋酸溶剂中反应成功地制备了3-烷基取代的咪唑并[1,5-a]吡啶. 实验结果表明: 微波法比传统的合成方法产率高、反应时间短. 产物的结构经过¹H NMR, MS和元素分析表征.     

Chemical constitution and activity of bipyridyliium herbicides. Part VIII. 4-Bromo-6,7-dihydrodipyrido[1,2-α:2′,1′-c]-pyrazinediium dibromide and related compounds

6-Chloro-2,2′-bipyridyl reacts with sodium alkoxides to afford the corresponding 6-alkoxy-2,2′-bipyridyls, which form 6,7-dihydro-4-oxodipyrido[1,2-a:2′,1′-c]pyrazinium bromide on treatment with 1,2-dibromoethane. 6-Chloro-2,2′-bipyridyl with this reagent gives 4-bromo-6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinediium dibromide.     

Mass spectral fragmentation pattern of 2,2′-Bipyridyls. Part IX. 6-Alkoxy-2,2′-bipyridyls

The mass spectral fragmentation patterns of 6-methoxy-, 6-ethoxy- and 6-propoxy-2,2 ′-bipyridyls are reported. The base peaks in the spectra of both the 6-methoxy and 6-ethoxy compounds are due to the M-lion of 6-methoxy-2,2′-bipyridyl, while the base peak with 6-propoxy-2,2- bipyridyl is due to a species formed by loss of C₃H₆ from the molecular ion.     

Synthesis of Bis(Trifluoromethyl)-2,2′- Bipyridines by Nickel Catalysed Homocoupling Reactions

Bis(trifluoromethyl)-2,2′-bipyridines have been synthesized in moderate yields by nickel or palladium catalysed homocoupling of 2-chloro(trifluoromethyl) pyridines.     

A convenient preparation of bipyridines through ligand coupling reaction with a-sulfurane formed by treatment of methyl 2-pyridyl sulfoxide with grignard reagents

6-substituted 2-methylsulfinyl pyridines react with Grignard reagents to afford 6,6′-disubstituted-2,2′-bipyridines (substituents: MeS, Cl, Br, H) in fair yields.     

Synthesis of (pyridinyl)-1,2,4-triazolo[4,3-a]pyridines

Methods for the synthesis of (pyridinyl)-1,2,4-triazolo[4,3-a]pyridines were developed. The principal route to the required intermediate 2-chloropyridines was based on rearrangements of mono N-oxides of 2,2′-bipyridine, 2,3′-bipyridine, 3,3′-bipyridine, 2,4′-bipyridine and 4,4′-bipyridine with phosphorus oxychloride. Reaction of 3,3′-bipyridine 1-oxide or 2,2′-bipyridine 1-oxide with phosphorus oxychloride gave mixtures of chloro isomers. Reaction with acetic anhydride, 3,3′-bipyridine 1-oxide and 2,2′-bipyridine 1-oxide gave exclusively [3,3′-bipyridine]-2(1H)-one and [2,2′-bipyridine]-6(1H)-one, respectively. 1,2,4-Triazolo[4,3-a]pyridines with pyridinyl groups at the 5,6,7 and 8 positions were synthesized.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part XIII. 6-Chloro- and 6-bromo-2,2′-bipyridyls

The mass spectra of 6-chloro- and 6-bromo-2,2′-bipyridyls are reported. The principal fragmentation route from the molecular ions involves loss of the halogen group to give the M-1 ion of 2,2′-bipyridyl which gives rise to the base peak in the spectra. Loss of HCN before loss of Cl occurs to a small extent with 6-chloro-2,2′-bipyridyl.     

Reactivities of dianions of pyridyl phenyl ketones

Substituted pyridylphenylcarbinols are formed in the reaction of the dianions of isomeric pyridyl phenyl ketones with alkyl halides, aldehydes, and benzonitrile. The reaction of the dianion of 3-pyridyl phenyl ketone with benzophenone, in contrast to the analogous reaction of the dianion of 2-pyridyl phenyl ketone, gives 5-benzoyl-2-diphenylhydroxymethyl-1,2-dihydropyridine. It is assumed that the observed reaction includes one-electron transfer and the formation of two anion radicals. Recombination of the anion radical of 3-pyridyl phenyl ketone leads to 5,5′-dibenzoyl-2,2′-di(1,2-dihydropyridyl).     

Synthesis and Properties of New Laser Dyes Containing 4-(2-Thienyl)Pyridine Skeleton

Abstract

Three 4-(oligothienyl)pyridines and four α,ω-di(4-pyridyl)oligo-thiophenes were prepared and the effect of conjugated thiophene rings on their fluorescence properties were examined. 4-(2,2′-Bithienyl-5-yl)pyridine and 2,5-di(4-pyridyl)thiophene exhibited laser dye emission upon pumping with a nitrogen laser and the conversion efficiency of the latter was 1.5 times as great as that of a commercial laser dye PBBO at 400 nm.     

Synthesis of chelating tertiary phosphine oxides via palladium-catalysed C–P bond formation

Bis(diphenylphosphine oxides) and bis(tert-butyl(phenyl)phosphine oxides) of 1,10-phenanthroline, 2,2′-bipyridine and pyridine were synthesised in good yields via the Pd(OAc)₂/dppf mediated cross-coupling reactions between 6,6′-dichloro-2,2′-bipyridine, 2,9-dichloro-1,10-phenanthroline, or 2,6-dichloropyridine and the corresponding secondary phosphine oxides. These compounds represent potential tetradentate chelating ligands for ions of f-block elements.     

Mass spectral fragmentation pattern of 2,2′-bipyridyls. Part II. 5-Hydroxy- and 5-alkoxy-2,2′-bipyridyls

The mass spectra of 5-hydroxy-, 5-methoxy-, 5-ethoxy- and 5-propoxy-2,2′-bipyridyls are reported. The fragmentation proposals are supported by high resolution mass measurements and metastable transitions.     

Dehydrogenative Synthesis of 2,2′‐Bipyridyls through Regioselective Pyridine Dimerization

2,2′‐Bipyridyls have been utilized as indispensable ligands in metal‐catalyzed reactions. The most streamlined approach for the synthesis of 2,2′‐bipyridyls is the dehydrogenative dimerization of unfunctionalized pyridine. Herein, we report on the palladium‐catalyzed dehydrogenative synthesis of 2,2′‐bipyridyl derivatives. The Pd catalysis effectively works with an Ag^I salt as the oxidant in the presence of pivalic acid. A variety of pyridines regioselectively react at the C2‐positions. This dimerization method is applicable for challenging substrates such as sterically hindered 3‐substituted pyridines, where the pyridines regioselectively react at the C2‐position. This reaction enables the concise synthesis of twisted 3,3′‐disubstituted‐2,2′‐bipyridyls as an underdeveloped class of ligands.     

Reactions of tris(2‐pyridyl)phosphine oxides with electrophiles: Formation of 5‐substituted 2,2′‐bipyridyls

The reaction of tris(2‐pyridyl)phosphine oxides with benzeneselenenyl chloride in methanol gave the corresponding 5‐phenylseleno‐2,2′‐bipyridyls together with a small amount of 2,2′‐bipyridyls. Similarly, the reaction with arenesulfenyl chlorides in aqueous acetonitrile afforded two kinds of coupling products, 5‐phenylthio‐2,2′‐bipyridyls and 2,2′‐bipyridyls. While in the reaction with arenesulfinyl chlorides in aqueous acetonitrile, four corresponding bipyridyl derivatives, 2,2′‐bipyridyls, 5‐arylthio‐2,2′‐bipyridyls, 5‐arylsulfinyl‐2,2′‐bipyridyls, and 5‐arylsulfonyl‐2,2′‐bipyridyls, were formed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:72–81, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10085     

Microwave-prompted rapid and efficient synthesis of 3-alkyl substituted imidazo[1,5-a]pyridines

Under regular heating and microwave irradiation, 3-alkyl substituted imidazo[1,5-a] pyridines were synthesized from 2,2＇- pyridil, di-2-pyridyl ketone and aliphatic aldehydes in the presence of ammonium acetate and acetic acid. Compared to the traditional heating condition, the reaction time under microwave irradiation was shorter and 3-alkyl imidazo[1,5-a]pyddines were given in higher yield.     

多重氢键自组装联萘酚和含氮化合物

作为相互识别的结果,(±)-2,2′-二羟基-1,1′-联萘酚可与4,4′,6,6′-四甲基-2,2′-联嘧啶、1,2-双(4-吡啶)乙烷、反式-1,2-双(4-吡啶)乙烯、4,4′-联吡啶-N,N′-双氧化物及双-2-吡啶基甲酮等多种含氮化合物分别形成外形良好的共晶化合物1,2,3,4及5.本文对5个共晶化合物的晶体...     

Triplet-sensitized photobehaviour of the three stereoisomers of 1,4-distyrylbenzene and some aza-analogues

The triplet spectral properties of the three stereoisomers (EE, ZE and ZZ) of 1,4-distyrylbenzene and some symmetric EE-aza-analogues, bearing a nitrogen heteroatom in the side (2′-pyridyl, 4′-pyridyl or 2′-quinolyl) or in the central (2,5-pyridine) arene rings, have been investigated by laser flash photolysis in different solvents and compared with those of the parent hydrocarbon. The quantum yields of the triplet-sensitized photoisomerization have also been measured. Adiabatic formation of the excited ³EE^* isomer by irradiation of the other geometrical isomers has been detected by transient spectroscopy. The effect of the substrate concentration on the sensitized photoisomerization quantum yield revealed the occurrence of a quantum chain process, as known for similar arylolefins.     

LIGAND EXCHANGE AND LIGAND COUPLING VIA THE σ-SULFURANE INTERMEDIATE IN THE REACTION OF ALKYL 2-PYRIDYL SULFOXIDE WITH GRIGNARD REAGENTS: CONVENIENT PREPARATION OF 2,2′-BIPYRIDINES

Abstract

The reaction between methyl 2-pyridyl sulfoxide (1) with Grignard reagents afforded 2,2′-bipyridine (2) in moderate yield. The reaction is considered to involve initial ligand exchange to generate 2-pyridylmagnesium halide which in the subsequent step attacks the original sulfoxide to form the σ-sulfurane that undergoes ligand coupling to afford 2. The reaction of t-butyl 2-pyridyl sulfoxide (3) with C₆H₅MgBr, however, gave only 2-phenylpyridine (4). This may be due to steric hindrance to the initial ligand exchange. Formation of 2 is a convenient process for preparation of 2,2′-bipyridines bearing various substituents.     

Chemistry of heterocyclic N-oxides and related compounds. 11. Reaction of pyridine N-oxide with metal ketyls and benzophenone dianions

The reaction of pyridine N-oxide with metal ketyls of benzophenone was studied. It is shown that diphenyl(2-pyridyl)carbinol N-oxide is formed with the lithium and sodium derivatives of benzophenone, whereas diphenyl(2-pyridyl)carbinol is formed with the potassium derivative of benzophenone. Diphenyl(2-pyridyl)carbinol N-oxide is obtained in lower yields in the reaction of pyridine N-oxide with benzophenone dianions. Pyridine and 4,4- and 2,2-dipyridyls are simultaneously formed in all of the reactions.See [1] for Communication 10.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–658, May, 1979.