Pyridine, 4-Phenyl

A reactor was charged with 150 ml of 2-ethoxyethanol, 50 ml of water, and 2-phenyl-pyridine (58 mmol) and then treated with iridium chloride(III) trihydrate (28 mmol) and refluxed for 12 hours under nitrogen. The solution was slowly cooled to ambient temperature and a precipitate isolated, which was washed with methanol, dried, and... 

Il)cycles formed with 2,2 -bipyridine or 1,10-phenanthroline type ligands to give a variety of target compounds (Scheme 18). These syntheses are more feasible than previous, where the complexes cis-[RuCl2(bpy)2] or fRuCl .(tpy)] have been used to cyclometalate 2-phenyl-pyridine and its derivatives (230-233). A bunch of diverse compounds have been prepared in good yields. Crystal structures of some of them are shown in Fig. 21 and their useful properties are summarized in Table IX. 

The free-radical arylation of pyridine N-oxides has not been studied systematically, alkylation not at all. When pyridine A-oxide was treated with benzene- and p-chlorobenzenediazonium salts only the 2-arylpyridine jV-oxides were isolated.393 No mention was made of the formation of the 3- and 4-aryl derivatives expected to be produced as well. The phenylation of pyridine N-oxide (diazoaminobenzene at 131° or 181° was found to be the most convenient source of phenyl radicals) was reinvestigated,394 and the reactivities of the nuclear positions found to be in the order 2 > 4 > 3, which is also that predicted6 on the basis of atom localization energy calculations. 2-Phenyl-pyridine N-oxide formed 71-81% of the total phenylation products, whereas the 3-isomer comprised only 5.6-9.6% of that total. The phenylpyridines were found among the by-products of the reaction. 

Scheme 4. (A) Proposed mechanism of the palladium-catalyzed 2-phenyl pyridine oxidative coupling reactions. Dependence of intermediates and products to the type of solvents were clearly observed. (B) Observed fragmentation pathways by loss of the product (left) and loss of phenyl pyridine which is followed by dissociation of PdH (right) 52. ...

S-carboline (178) but cyclized to pyrido[l,2 ]indazole (176) Carboline 178 was however obtained by heating 3-azido-2-phenyl-pyridine (177) . 

Absorption spectra and emissive properties of Ir(ppy)3 and related Ir(III) complexes (where ppy=2-phenyl-pyridine) have been extensively studied in solution and in solid state [145-149]. The size of the ligands together with the presence of a heavy metal atom has made the theoretical study of such molecules challenging until recently. In a recent TD-DFT (B3LYP) study [150] the low-lying triplet and singlet excited states of three related Ir(III) complexes Ir(ppy)3, Ir(ppy)2(acac) and Ir(ppy)2(bza) (where acac=acetoy-... 

Adachi, C., Baldo, M. A., Forrest, S. R. et al. 2000. High efficiency organic elec-trophosphorescent devices with tris(2-phenyl-pyridine)Iridium doped into electron-transporting materials. Appl. Phys. Lett. 77 904. 

The first synthesis of 5-carboline (DC-141) was achieved by the thermal decomposition of 3-azidopyridine (DC-140), prepared from 3-amino-2-phenyl-pyridine (IX-139). When the diazonium salt from 2-amino-yV-methyl-, 3 -... 

Other approach for the synthesis of ketones is the acylation of het-eroarenes discovered by Kakiuchi and further developed hy Frost. Kakiuchi presented the acylation of benzo[ft]quinoline and 2-phenyl-pyridine with aromatic and vinylic acyl chlorides using [RuCl2(PPh3)3] in toluene at 120 °C (Scheme 21). ° Later, Frost extended this transformation to the reaction of 1-arylpyrazoles and aliphatic acyl chlorides by using [RuCl2(p-cymene)]2 and PCya (Scheme 21). Interestingly, higher yields of the acylation products were obtained for the more sterically... 

In contrast to all the C-C bond formations described previously, C-H cyanations are much rarer. This might be due to the possible strong coordination of free CN ligands to transition metal centers, which would preclude C-H activation as the first step of the catalytic cycle for C-H functionalization. The first C-CN bond formation was reported in 2006 by Yu and coworkers along with a series of Cu-catalyzed and Cu-mediated C-H functionalizations of 2-phenyl pyridine (Scheme 23.24) [88]. C-CN bond formations can thus be achieved with Me SiCN or CH NO as cyanating reagents in the presence of 1 equivalent of Cu(OAc)2 and air. 

Together with C-H phosphorylations, C-H sulfenylations are rather rare among the large body of literature covering chelate-assisted C-H functionalizations. An initial example of this type of reactivity was reported by Yu and coworkers, using PhSH orMeSSMe as reagents for the sulfenylation of 2-phenyl pyridine (Scheme 23.42) [88]. 

Oxy.4-methyl-2-phenyl-pyridin 21 H 71. 8-Oxy-7-allyl-chmolin 21II72. 6 Oxy.2-methyl-5-Tmy. ohhiolin 21II72. 6-Oxy-8-methyl-5-vinyl-chinoUn 21II72. 4-Oxy-2.3-cyolopenteDO-chinolin 21II72. 

Oxy-2.phenyl.pyridin 21II70. 6-Ozy-2-phenyl-pyridin 21,123. 2-[2-Oxy-phenyl1-pyridin 211227, II70. 2-[4-Oxy-idienyl]-pyndin 211227, H 70. O-Oxy- vinyl-chinoHn 21 n 70. N-Phenyl-a-pyridon 21II 231. N-Phenyl-y-pyridon 21, 270, H 234. 

Fig. 3.19 Photoisomerisation in the coordination sphere. Left-, cis-trans isomerisation of Ru(II) complex Right mer/fac isomerisation of an IXIII) complex with three cyclometallating ligands, such as 2-phenyl-pyridine...

As a bidentate ligand, 2,2 -bipyridine chelates through the two nitrogen centers (1). While this is true for most of the transition metals, stable complexes with C,N -coordination (2) are also formed with metal ions such as Ir(III), Pt(II) and Pd(II). Stable ortho-metalated complexes are also obtained with other ligands such as 2-phenyl pyridine. These ortho-metalated complexes are emissive in fluid solutions and exhibit rich photochemistry. 

High-oxidation-state palladium complexes are frequently involved in oxidative C-H functionalization processes [43]. Generally, a Pd(II) intermediate that is formed via CH activation or oxidative addition to C-X is oxidized further to the corresponding high-oxidation-state Pd intermediate (see Figure 4.11). For C-H to C-C or C-X bond transformations, mononuclear Pd(IV) and also dinuclear Pd(III)-Pd(III) complexes have been proposed to be involved for substrates based on the 2-phenyl pyridine framework [44]. The irreversible C-C or C-X... 

In 2008, Jones et cd. disclosed a stoichiometric Rh(III)-mediated reaction of JV-benzylidenemethylamine with dimethyl acetylenedicarboxylate to give the corresponding isoquinolinium salt [52a]. Inspired by this work, in 2012 we developed a Rh(III)-catalyzed one-pot synthesis of isoquinolinium salts 104 from benzaldehydes, primary amines, and internal alkynes by C-H activation and annulation [52b]. This was the first report for the synthesis of isoquinohnium salts by catalytic C-H activation. It is noteworthy that the current procedure was successfully apphed to the total synthesis of isoquinolinone alkaloid oxy-chelerythrine 105 (Eq. (5.99)). In 2013, our group and Huang independently found that various isoquinohnium salts could be synthesized from aryl ketimines, 2-phenyl pyridines, and alkynes under similar reaction conditions, as shown in Eqs. (5.100)-(5.102) [52c-e]. 

Pyridine 1-oxide reacts with adamantane-1-thiol in acetic anhydride to give 2- and 3-(l-adamantanethio)pyridines and their tetrahydropyridine analogues. Corresponding butylthio-substituted pyridines are obtained using Bu SH or Bu SH in this reaction in the presence of a chloroformic acid derivative. No complications arise in the use of 3-bromopyridine 1-oxide and KSH for the synthesis of 3,3 -dipyridyl sulphide. 2-Methyl- or 2-phenyl-pyridine is converted into its 5-alkylthio-homologue by reaction of the pyridine-MeLi adduct with a dialkyl disulphide. ... 

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