Pyridine iV-oxidation

Oxygen donors like peroxy acids, ozone, and pyridine IV-oxides cause carbon-carbon cleavage, perhaps by formation of a perepoxide (43 Scheme 30) (81JCS(P1)1871). Other oxidants have also been reported to react with oxiranes (64HC( 19-1)228). 

Conditions (a) 1-5 mol% catalyst, w-CPBA/NMO, -78°C, CH2CI2. (b) 1-5 mol% catalyst, NaOCl, 4-phenylpyridine iV-oxide, 0°C, CH2CI2. (c) 1-5 mol% catalyst, NaOCl, pyridine iV-oxide, 0°C, CH2CI2. (d) Solvent = diethyl ether... 

Dichlorocarbene, generated in a variety of ways, was shown to deoxygenate pyridine iV-oxide, being itself oxidized to phosgene. 

The phenylation of quinoline with dibenzoyl peroxide was studied by Pausacker, who obtained all seven monophenylated quinolines in relative amounts shown in (4).- He also examined the phenylation of pyridine-iV-oxide with diazoaminobenzene and obtained the results shown in (5). ... 

Mono- and dilithio derivatives of p-tosylmethyl isocyanide 297a were shown to display interesting reactions. Reaction of the monoanion with unsaturated esters was shown to give pyrrole derivatives . Dianion 297b was found to add to the carbon-nitrogen double bonds of isoquinoline, quinoline and quinoxaline affording compounds 298, 299 and 300, respectively. In the reactions with pyridine iV-oxide and pyridazine iV-oxide, unstable open-chain products 301 and 302 were obtained . 

Slow addition of hexamethyldisilane in THF to pyridine iV-oxide and tetrabutylammonium fluoride in THF effected smooth reduction to pyridine, while addition of undiluted fluoride led to an explosion on two occasions. 

V-Nitroamino)pyridine IV-oxide (lV-Nitro-4-pyridinamine 1-oxide)... 

Pyridine iV-oxide, Tetrabutylammonium fluoride See Pyridine /V-oxidc Hexamethyldisilane, Tetrabutylammonium fluoride See other alkylsilanes... 

Closure of the oxadiazole ring is still achieved through cycloaddition between pyridine iV-oxides and isocyanates, affording adducts such as 142 (Scheme 38) <1995T6451>. Nonaromatic imine fV-oxides exhibited similar reactivities, since azasugar-derived fV-oxides as a mixture of 143 and 144 underwent cycloaddition reactions in the presence of phenyl isocyanate or trichloroacetonitrile. Compounds 145 and 146 (Scheme 39) were obtained from the aldoxime W-oxide 143 two other regioisomeric heterocycles arose from the ketoxime derivative 144 <1996T4467>. 

Recently a new synthetic pathway to tctrazolo[l,5-z/ pyridine has been explored by Keith <2006JOC9540>. According to this new procedure, pyridine iV-oxides can be treated by sulfonyl or phosphoryl azide to furnish tetrazolo[ 1,5-tf]pyridines in one reaction step in medium to good yields (30-100%). 

Nickel(II) complexes of a variety of bidentate sulfoxide ligands have been reported (326,378,413) and [NiL3][C104]2 species reported where L is the unusual bidentate ligand 2-(ethysulfinyl)pyridine-iV-oxide. Bidentate 0,0-coordination via sulfoxide and pyridine-N-oxide donors is assigned from infrared data (63). 

The new ligand, 2.3-di-(2-pyridine iV-oxide)quinoxaline (83) has been prepared and the complexes [CoCl2L],1.5H20, [CoBr2L],H20, and [C0I2L],-H2O isolated from its reaction with the appropriate cobalt(ii) salt in ethanol. All three complexes are tetrahedral s ... 

Figure 10 Dimensions of crystallographically independent molecules of pyridine IV-oxide...

Figure 11 Dimensions of pyridine IV-oxide in the complex [CutCsHsNOfCb-hbO ...

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