Pyridyl bis

Treating 5.5 g of 2-amino-4,5-dimethylthiazole HCl with 0.66 g of solid sodium hydroxide 15 min at 220°C yields 53% of 4.4. 5.5 -tetramethyT 2,2 -dithiazolylamine, whose structure w as proved by identification with the produa obtained from the reaction between dithiobiuret and 3-bromo-2-butanone (467). This result is comparable to the reaction between 2-aminopyridine and its hydrochloride to yield bis(pyridyl-2)amine (468). Gronowitz applied this reaction to 2-aminothiazole, refluxing it with its hydrochloride 4 hr in benzene and obtained the dimeric 2-aminothiazole (236). He proposed a mechanism (Scheme 143) that involves the addition of a proton to the 5-position of the ring to give 234. The carbocation formed then reacts on the 5-position of a second... 

This group has also developed two ring-contraction systems of potential use in crown synthesis. In the first of these, extrusion of a phenylphosphine oxide unit results from treatment with alkoxide ion. In the second, similar conditions initiated decarbonyla-tion of a bis-pyridyl ketone Despite the apparent potential of these methods for crown synthesis, direct formation of crowns by processes which involve them do not appear to have enjoyed great success thus far. 

Pyridin wird in verdiinnter Schwefelsaure an Blei-Kathoden zu Piperidin (90% d.Th) reduziert2 3. 2,2 -Bi-pyridyl (III) kann dagegen je naeh den Elcktrolysebedingungen zu 1,4-Dihydro- (IV) bzw.2,3,4,5-Tetrahydro-2,2 -bi-pyridyl (V) reduziert werden (Queck-silber-Kathode, geteilte Zelle)4 ... 

Das isomere 3,3 -Bi-pyridyl wird an Blei-Kathoden in verdiinnter Mineralsaure voll-standighydriertund man erhalt-nach der Neutralisation mit 30%iger Kalilauge-gleiche Mengen an erythro- und threo-3,3 -Bi-piperidyl (geteilte Zelle —1,15 V 44% d.Th.)5. 

Materials. 5-Methyl-1,4-hexadiene was obtained by the codimerization of isoprene and ethylene with a catalyst (18) consisting of iron octanoate, triethylaluminum and 2,2 -bi-pyridyl. The product mixture which contained principally 5-methyl-1,4-hexadiene and 4-methy1-1,4-hexadiene was fractionated through a Podbielniack column to yield high purity (>99%) 5-methylxhexadiene, b.p. 92.80C,njj 1.4250 (Lit. (19) b.p. 88-89°C, np 1.4249). 1-Hexene (99.9% purity), 1-decene (99.6% purity), 4-methyl-1-hexene (99.5% purity) and 5-methyl-l-hexene (99.7% purity) were obtained from Chemical Samples Co. 6-TiCl3 AA (Stauffer Chemical Co.j contains 0.33 mole AICI3 per mole of TiClj). Diethylaluminum Chloride was obtained from Texas Alkyls (1.5 M in hexane). 

The aforementioned polymer-supported bis-pyridyl ligand has also been applied in microwave-assisted asymmetric allylic alkylation [140], a key step in the enantio-selective synthesis of (R)-baclofen (Scheme 7.118), as reported by Moberg and coworkers. The ( (-enantiomer is a useful agonist of the GABAb (y-aminobutyric acid) receptor, and the racemic form is used as a muscle relaxant (antispasmodic). Under microwave heating, the enantioselectivity could be improved to 89% when using toluene as solvent (see also Scheme 6.52) [140],... 

Electrochemical impedance spectroscopy was used to determine the effect of isomers of 2,5-bis( -pyridyl)-l,3,4-thiadiazole 36 (n 2 or 3) on the corrosion of mild steel in perchloric acid solution <2002MI197>. The inhibition efficiency was structure dependent and the 3-pyridyl gave better inhibition than the 2-pyridyl. X-ray photoelectron spectroscopy helped establish the 3-pyridyl thiadiazoles mode of action toward corrosion. Adsorption of the 3-pyridyl on the mild steel surface in 1M HCIO4 follows the Langmuir adsorption isotherm model and the surface analysis showed corrosion inhibition by the 3-pyridyl derivative is due to the formation of chemisorbed film on the steel surface. 

A similar mechanism could operate also for bis(imino)pyridyl Fe(II)-based catalysts which have been reported to afford isospecific chain-end controlled propene polymerization occurring through secondary monomer insertion.138139 In fact, preliminary calculations indicate that the chirality of the growing chain would determine a chiral conformation of the bis-pyridyl ligand, which in turn would discriminate between the two monomer enantiofaces. 

Barluenga et al. developed a novel exo-endo-cyclization of a,codiynes by use of bis(pyridyl) iodonium(I)-tetrafluoroborate (IPy2BF4) as catalyst.1171 The reaction follows a cationic-cationic pathway (scheme 6). First the electrophilic iodo ion reacts with the triple bond of 26 to give the relative stable vinyl cation 28. Ring closure leads to a seven-... 

Pattabiraman M, Natarajan A, Kaliappan R, Mague JT, Ramamurthy V (2005) Template directed photodimerization of trails-1,2-bis( -pyridyl)ethylenes and stilbazoles in water. Chem Commun 36 4542-4544... 

DR. SIDERS The edge atoms on the rings of the tris-bi-pyridyl complexes that we considered are a long way out from the central metal ions. For that reason we thought that an estimate such as Hopfield s, based on a carbon-carbon overlap, would be more appropriate than one based on a metal-metal overlap. 

NMR spectrum showing the presence of a 3-substituted pyridine with four nonequivalent methylene units in the substituent, and by its conversion to 2,3-bi-pyridyl with chloranil (26). Its synthesis was made by condensation of A -ben-zoylpiperidone (258) with ethyl nicotinate (259) followed by heating with concentrated hydrochloric acid, resulting in hydrolysis, decarboxylation, and ring closure (Scheme 18) 401). Application of the Mundy A-acyllactam rearrangement to A-nicotinoylpiperidone (261) has also led to a synthesis of anaba-seine (8) (Scheme 18) 402). 

Benzoato- 0,0 )(tert-butylperoxy)[l, 3-bis(pyridyl-2-imino)isoindoline-... 

Schiff base formation occurs normally with 3-aminopyridine (69CR(C)(269)1319> and aldehydes, but imines of 2-aminopyridine, though isolable, are less stable and bis(pyridyl-amino) compounds (e.g. 93) are readily formed. 9-Aminoacridine fails to react with benzal-dehyde. Nitrosobenzenes condense with aminopyridines in alkali (but not in acetic acid) to give azopyridines (Scheme 82). 

An jco-OT o-cyclisation of a,o -diynes promoted by bis(pyridyl)iodonium(i) tetrafluoroborate (IPy2BF4) has been described for the first time and is an excellent route for accessing a variety of sulfur-containing heterocycles when employing alkynyl sulfides (Scheme 49) <1998AGE3136>. 

Wasserstoff durch eine Losung von (2,2 -Bi-pyridyl)-(l,5-hexadien)-rhodium-hexafluorophosphat und festem Natriumhydroxid in Methanol/Tetrahydrofuran leiten. Nach 30 min Hexandisaure-dinitril zugeben und das Gemisch bei 100° unter 1750 kPa WasserstofT-Druck 2h hydrieren Ausbeute 73%2. 

Pr Pro ptz pvp py pyca pycaH pyo pyr pys pySH pySSpy iso-propyl = 2-propyl proline phenothiazine polyvinyl pyridine pyridine pyridine-2-carboxylato(l -) pyridine-2-carboxylic acid pyridine iV-oxide pyrimidine pyridine-2-thiolato(l -) pyridine-2-thiol 2,2 -bis(pyridyl) disulfide... 

The oxidative effects of silver(II) complexes of pyridine carboxylates have been studied for a variety of substrates. With ar-amino acids, a rapid reaction occurred at 70 °C in aqueous solution with bis(pyridyl-2-carboxylato)silver(II). 4 The product was the next lower homologous aldehyde and yields were generally greater than 80%. Other substrates included primary and secondary amines, alcohols, monosaccharide derivatives, alkenes, arylalkanes and arylalkanols.90 Only minor differences were detected in efficiencies when 2-, 3- or 4-mono-, or 2,3-di-carboxylates were used as the oxidant. 

A second example is the recently reported singlet-triplet equilibrium in a Mo(II) complex, cis-[Mo(bipy)2(OPri)2] (31). The interpretation of the magnetism is complicated by the possibility that the equilibrium is not entirely metal centered, but involves charge transfer to the bi-pyridyl ligands. Because a strong field is required to spin pair the d4 configuration, however, it is not impossible that examples exist among Mo(II) chemistry. The possible dynamics are subject to considerations similar to those which apply to Mn(III). 

Perfluoro-2,2 -bipyridyl (12) with sodium methoxide yields heptafluoro-4-methoxy-2,2 -bi-pyridyl and hexafluoro-4,4 -dimethoxy-2,2 -bipyridyl.124... 

Palladium 2.2 -Bi-pyridyl-bis-[penta-fluorophenyl]- lll/9ll 822 (L2PdC l2 + F5C6 — I i)... 

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