2-Pyridyl chloroformate

Ketone synthesis.4 Organocuprates do not ordinarily react with esters at low temperatures, but they react satisfactorily with 2-pyridyl esters to provide ketones. These esters are readily available by reaction of 2-pyridyl chloroformate, an acid, and N(C2H5)3 catalyzed by DMAP. 

Other acylating agents are similarly effective in the formation of ketones by reaction with homocuprates. Kim has demonstrated that activated esters such as the 2-pyridyl carboxylates are satisfactory cuprate traps.These esters can be prepared from carboxylic acids and 2-pyridyl chloroformate, provided a catalytic amount of DMAP is utilized (Scheme 35). 

The first identified complexes of unsubstituted thiazole were described by Erlenmeyer and Schmid (461) they were obtained by dissolution in absolute alcohol of both thiazole and an anhydrous cobalt(II) salt (Table 1-62). Heating the a-CoCri 2Th complex in chloroform gives the 0 isomer, which on standirtg at room temperature reverses back to the a form. According to Hant2sch (462), these isomers correspond to a cis-trans isomerism. Several complexes of 2,2 -(183) and 4,4 -dithiazolyl (184) were also prepared and found similar to pyridyl analogs (185) (Table 1-63). Zn(II), Fe(II), Co(II), Ni(II) and Cu(II) chelates of 2.4-/>is(2-pyridyl)thiazole (186) and (2-pyridylamino)-4-(2-pyridy])thiazole (187) have been investigated. The formation constants for species MLr, and ML -" (L = 186 or 187) have been calculated from data obtained by potentiometric, spectrophotometric, and partition techniques. 

Upon completion of the addition, the mixture is agitated for 7 hours at ambient temperature. The solution is then poured into 3 liters of water/ice obtaining a clear solution of dark yellow color which is rendered alkaline upon phenolphthalein with 30% NaOH and extracted with ethyl ether to eliminate the majority of the pyridine. The mixture is filtered with active charcoal, the pH adjusted to 8 with hydrochloric acid 1 1 and extracted with chloroform to remove the 4,4 -dihydroxydiphenyl-(2-pyridyl)-methane which has not reacted. 

The mixture is poured onto excess ice, acidified with concentrated hydrochloric acid, the ether layer sepatated and extracted with water (1 x 200 cc). The combined aqueous extracts are washed with ether (1 x 200 cc) basified with 0.880 ammonia and extracted with chloroform (3 x 350 cc) the extract is washed with water (2 x 100 cc), dried over sodium sulfate, evaporated, and the residue extracted with boiling light petroleum (BP 60° to 80°C 10 volumes), filtered hot and evaporated to dryness. The residue is recrystallized from alcohol to give a cream solid (119 g, 80%), Pi/IP 117° to 118°C. Recrystallization gives 1-(4-methylphenyl)-1-(2-pyridyl)-3-pyrrolidonopropan-1-ol, MP 119° to 120°C. 

Bhat et al. [199] used complexation with the bis(ethylenediamine) copper (II) cation as the basis of a method for estimating anionic surfactants in fresh estuarine and seawater samples. The complex is extracted into chloroform, and copper is measured spectrophotometrically in the extract using l,2(pyridyl azo)-2-naphthol. Using the same extraction system these workers were able to improve the detection limit of the method to 5 pg/1 (as linear alkyl sulfonic acid) in fresh estuarine and seawater samples. 

Evidence for metabolic a-hydroxylation of NNN was first obtained through in vitro experiments. NNN-2 -l C was incubated with rat liver microsomes, O2 and an NADPH generating system. The resulting mixtures were added to DNP reagent and analyzed by preparative TLC or HPLC. The DNPs of the keto alcohol, 4-hydroxy-l-(3-pyridyl)-l-butanone (0.6% from NNN) and of 4—hydroxy-4-C3-pyr— idyDbutanal (0.3% from NNN) were both identified by comparison of their mass spectra to reference samples. These products, which were not present in controls, resulted from 2 -hydroxylation and 5 -hydroxylation of NNN, respectively (see Figure 12). Another product of 2 -hydroxylation, myosmine (0.6% from NNN) was identi-by GLC-MS analysis of incubation mixtures, after extraction with chloroform. 

A mixture consisting of the step 1 product (4.7 mmol), 4-(2-pyridyl) benzaldehyde (9.3 mmol), and 500 ml of toluene was stirred at ambient temperature for several hours and then treated with silver trifluoromethanesulfonate (9.3 mmol). The mixture refluxed for 3 hours and was then cooled to ambient temperature and filtered through Celite and then concentrated. The residue was purified by silica gel column chromatography using chloroform/ethyl acetate, 19 1, respectively, and then recrystallized in CH2CI2/methanol and 0.95 g of product isolated. 

It was necessary to assume that l-(4-pyridyl) pyridinium dichloride was formed without the formation of pyridinium chloride in the chloride reaction mixture, in order to account for the stoichiometries observed. The absence of the characteristic spectra of pyridinium chloride from samples of chloroform-soluble residues supported this assumption. However, for similar reasons it was necessary to conclude that pyridinium bromide was a product of the bromide reaction. The difference between the two reactions in this respect may be explained by the relative solubilities of the two halide salts of the protonated l-(4-pyridyl) pyridinium ion in pyridine. This point, however, was not pursued further in this investigation. 

Two modifications of the well-known benzothiazole preparation have been employed to prepare unusual heteropoly cycles. Konig et al.ils treated l-thiocarbamoyl-l,2,3,4-tetrahydroquinoline (236) with bromine in chloroform to give the thiazolo[3,4,5-J,i]quinoline derivative 237. In a process which requires disruption of the resonance stabilization of the pyridine ring, Harris416 reported that treatment of l-(2-pyridyl)-2-thiourcas with sulfuryl chloride or with bromine gives the hydrohalide salts of 2-imino-2//-[l,2,4]thiadiazolo[2,3-a]pyridines (238). 

The solution of 5.0 g of l-(4-pyridyl)-2-imidazolidinone in 45 ml of water is hydrogenated over 0.8 g of 10% ruthenium on carbon at 120°C and 120 atm until the hydrogen absorption ceases. It is filtered, the filtrate evaporated, the residue taken up in chloroform, the solution dried, evaporated to yield the 1-(4-piperidyl)-2-imidazolidinone, melting point 155°-157°C (recrystallized from methylene chloride-petroleum ether). 

To 78 ml of a 1 M solution of diborane in tetrahydrofuran under nitrogen and cooled to 0°C is added dropwise over a period of 40 minutes 13.5 g of N-tert-butyl-2-(5-benzyloxy-6-hydroxymethyl-2-pyridyl)-2-hydroxyacetamide in 250 ml of the same solvent. The reaction mixture is allowed to stir at room temperature for 3.5 hours, and is then heated to reflux for 30 minutes and cooled to room temperature. Hydrogen chloride (70 ml, 1.34 N) in ethanol is added dropwise, followed by the addition of 300 ml of ether. The mixture is allowed to stir for 1 hour and is then filtered, yielding 11.0 g, melting point 202°C (dec.). The hydrochloride dissolved in water is treated with a sodium hydroxide solution to pH 11 and is extracted into chloroform (2 x 250 ml). 

To a stirred suspension containing 5.1 g of 57% sodium hydride dispersed in mineral oil and 150 ml of dimethylformamide was added in portions 32.6 g of ethyl l,4-dihydro-4-oxo-7-(4-pyridyl)-3-quinolinecarboxylate [tautomeric with ethyl 4-hydroxy-7-(4-pyridyl)-3-quinolinecarboxylate] followed by the addition of 18.7 g of ethyl iodide. The resulting reaction mixture was heated on a steam bath for three hours with stirring and then concentrated in vacuo to remove the solvent. The semisolid residue was shaken well with a mixture of chloroform and water, and a small quantity of amorphous brown solid was filtered off. The layers were separated and the chloroform layer was evaporated in vacuo to remove it. 

Coordination polymer nanotubes have been prepared using Hg2+-mediated coassembly of two ligands, tetrapyr-idylporphine (TPyP) 128 and tris(4-pyridyl)-l,3,5-triazine (TPyTa) 129 (which is readily formed by the trimerization of 4-cyanopyridine under acid- or base-catalyzed conditions), at the water-chloroform interface <2006CC3175>. 

Ng et al. first reported the axial ligation of zinc(II) l,8,15,22-tetrakis(3-pentyloxy) phthalocyanine (1) with meso-pyridyl porphyrins 2 and 3 in chloroform, which form the corresponding edge-to-face dyad and pentad, respectively [25], As shown by UV-Vis spectroscopy, the ground-state tt-tt interactions between the perpendicularly disposed macrocycles in these arrays are insignificant. Upon mixing of phthalocyanine 1, zinc(II) meso-tetra(/Molyl)porphyrin, and 4,4/-bipyridine in chloroform, the formation of a face-to-face hetero-dyad was also inferred by fluorescence quenching experiments. 

Perylenediimides represent another class of photoactive dyes which are characterized by their strong fluorescence emission and facile electrochemical reduction. Recently, a supramolecular bis(phthalocyanine)-perylenediimide hetero-triad (compound 42) has been assembled through axial coordination [47]. Treatment of perylenediimide 43, which has two 4-pyridyl substituents at the imido positions, with 2.5 equiv. of ruthenium(II) phthalocyanine 44 in chloroform affords 42 in 68% yield (Scheme 3). This array shows remarkable stability in solution due to the robustness of the ruthenium-pyridyl bond. Its electronic absorption spectrum is essentially the sum of the spectra of its molecular components 43 and 44 in... 

The kind of attachment of the metal coordinating groups to the cavitand is an important structure-defining parameter. Hong et al. studied the self-assembly of a cavitand 15 functionalized with pyridyl groups via flexible ether linkages (Fig. 5) [48, 49]. Due to the conformational freedom of the connection, intramolecular coordination of the metal (Pt2+ and Pd2+) centers is observed in competition with intermolecular complexation leading to the supramolecular capsules 16a-b. While the capsules 16a b and the half-capsules 17a-b are in dynamic equilibrium in nitromethane, the dimeric capsule is formed exclusively in chloroform/methanol mixtures. 

Flexibility in ligands can lead to subtle or dramatic changes in architecture. For example, l,2-bis(pyridyl)ethane, dipy-Et, can readily adapt gauche or anti conformations. In the case of [Co(dipy-Et), 5(N03)2]n, which contains a T-shape node, infinite molecular ladders which contain six molecules of chloroform per cavity exist as the most commonly encountered architecture (Figure 3A).45b In such a situation all spacer ligands are necessarily anti. However, under certain crystal-... 

To a solution of 5-isopropyl-N-[6-(4-hydroxy-2-butynyloxy)-5-(o-methoxyphenoxy)-2-(4-pyridyl)-4-pyrimidinyl]-2-pyridine sulfonamide (50 mg) and 4-dimethylaminopyridine (10 mg) dissolved in 5 ml chloroform was added 25 p>l n-buty 1-isocyanate and the solution stirred for 42 hours at 65 °C. After 6, 18, and 28 hours additional 25 p>l portions of n-butyl isocyanate were added. Thereafter, the solution was diluted with 50 ml EtOAc, dried, purified by chromatography on silica using hexane/EtOAc, 1 1, then CH2CI2 containing 4% methyl alcohol, and the product isolated. MS data supplied. 

Pyridyl)ethyl-p-nitrophenyl carbonate, The reagent is prepared by reaction of (2-pyridyl)ethanol and p-nitrophenyl chloroformate. 

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