Nitrones butyl

Oxaziridine formation by photoisomerization of nitrones was discovered almost simultaneously with the peracid procedure (58JOC65l>. The t-butyl nitrones of benzaldehyde and 4-nitrobenzaldehyde yielded about 90% of oxaziridines (254) and (255) on UV irradiation. 

A-tert-Butyl a-phenyl nitrone [3376-24-7] M 177.2, m 73-74 . Crystd from hexane. 

The rearrangement of phenyl- er -butyl nitrone to the isomeric oxazirane (9) occurred in 95% yield on irradiation in acetonitrile for 2 hr. Because 2-ieri-butyl-3-phenyloxazirane (9) can be reconverted into the more stable nitrone, the photochemical reaction involves the conversion of radiation energy into chemical energy. 

The UV and IR spectra eliminate structures with a CN double bond. The isomerism of nitrones and oxaziranes thus cannot be a result of CIS or traris arrangement of substituents about a double bond. The carbon atoms of an oxazirane are still at the oxidation level of the carbonyl compound used in its syntheses. By acid hydrolysis, for example, 2-terf-butyl-3-phenyloxazirane (9) can be split into benzaldehyde and tert-butylhydroxylamine fEq. (8)]. ... 

Reduction with lithium aluminum hydride allows a differentiation from the isomeric nitrones. Whereas 2-tert-butyl-3-phenyloxazirane (9) gives benzylidene-tert-butylamine [Eq. (10)], reduction of the isomeric nitrone leads to iV-benzyl-xV-fert-butylbydroxylaminc [Eq. 

The rearrangement of 2-fert-butyl-3-phenyloxazirane to the isomeric nitrone is quantitative on refluxing 3 days in acetonitrile [Eq. (25)]. ... 

In an analogous study by Meske, the impact of various oxazaborolidinone catalysts for the 1,3-dipolar cycloaddition reactions between acyclic nitrones and vinyl ethers was studied [31]. Both the diastereo- and the enantioselectivities obtained in this work were low. The highest enantioselectivity was obtained by the application of 100 mol% of the tert-butyl-substituted oxazaborolidinone catalyst 3d [27, 32] in the 1,3-dipolar cycloaddition reaction between nitrone la and ethyl vinyl ether 8a giving endo-9a and exo-9a in 42% and 27% isolated yield, respectively, with up to 20% ee for endo-9a as the best result (Scheme 6.10). 

Nitrones arc generally more stable than nitroso-compounds and arc therefore easier to handle. However, the nitroxides formed by reaction with nitrones [e.g. phenyl /-butyl nitrone (109)]483 484 have the radical center one carbon removed from the trapped radical (Scheme 3.86). The LPR spectra are therefore less sensitive to the nature of that radical and there is greater difficulty in resolving and assigning signals. Nitrones are generally less efficient traps than nitroso-compounds.476... 

Barth A, Barth L, Newell DW. Combination therapy with mk-801 and alpha-phenyl-tert-butyl-nitrone enhances protection against ischemic neuronal damage in organotypic hippocampal slice cultures. Exp Neurol 1996 141 330-336. 

Kalyanaraman, B., Joseph, J. and Parthasarthy, S. (1991). The spin trap, a-phenyl N-test butyl nitrone inhibits the oxidative modication of low density lipoprotein. FEBS Lett. 280,17-20. 

Parratt, J.R. and Wainwright, C.L. (1987). Failure of allopurinol and a spin trapping agent N- -butyl-alpha-phenyl nitrone to modify significantly ischaemia and tepcrfiision-induced arrhythmias. Br. J. Pharmacol. 91, 49-59. 

Yu, T.L., Gu, J.L., Lysko, P.G., Cheng, H.Y., Barone, F.C. and Feuerstein, G. (1992). Neuroprotective effects of phenyl-f-butyl-nitrone in gerbil global brain ischemia and in cultured rat cerebellar neurons. Brain Res. 574, 193-197. 

Ohnishi (Sakamoto etal., 1991) has described an oligomeric derivative of prostaglandin Bi (PGB2) and ascorbic acid. In a rat bilateral carotid occlusion-reperfiision injury complicated by haemorrhagic hypotension, this compound reduced a-phenyl-r-butyl nitrone (PBN) spin-trapped radicals and thiobarbituric acid-reactive products (TBARs) (a measure of lipid peroxidation) in isolated... 

Recendy, PEN, a-4-pyridyl-oxide-N-t-butyl nitrone (POEN) or 5-5,dimethyl-1, pyrroline-N-oxide (DMPO) were evaluated in models of experimental shock (endo-toxic, traumatic and mesenteric artery occlusion in rats). All three nitrones, when given prior to the insult intraperitoneally, were protective. When the nitrone s spin trapping ability was inactivated by exposure to solar light and air, they were no longer efficacious (Novelli, 1992). 

Bolli, R, Patel, B.S., Jeroudi, M.O., Lai, E.K. and McCay, P.B. (1988). Demonstration of free radical generation in stunned myocardium of intact dogs with the use of the spin trap a-phenyl-N-ferr-butyl nitrone. J. Clin. Invest. 82, 476-485. 

As an alternative process, the nitrone (138 R Cl OCl Ph) yields a mixture of diastereoisomeric (benzyloxymethyl)phosphonic derivatives of which (141) is the main component acidolysis and hydrogenolytic debenzylation lead to phosphoserine (143), the (S) chirality of which was demonstrated by )(-ray analysis of the derivative (144). In a further variation, the di-tert-butyl... 

The presence of /3-hydrogen in the nitroxide radical may lead to disproportionation reactions. In spin-trapping experiments, N-t-butyl-a-phenyl nitrone yields rather unstable spin adducts. This type of radical can be stabilized by coordination to Nin. The Ni11 complex with N-oxy-A-r-butyl-(2-pyridyl)phenylmethanamine (923) reveals a distorted octahedral geometry with antiferromagnetic interactions between the unpaired electrons of the metal ion and the radical spins.00... 

DMD was employed to oxidize /Va-carbobenzyloxy (Cbz)-L-lysine tert-butyl ester to the corresponding lysine-based dimethyl nitrone, an important synthetic intermediate of the mycobactins (78). 

The same conclusions about the effect of substituents and protonation on chemical a-C shift have been made from the spectra of a-substituted N-tert-butyl-nitrones (388). 

Recently, tert- butyl (phenylsulfonyl)alkyl-A-hydroxycarbamates (343), which are readily obtained from the reaction of aldehydes and tert -butyl-A -hydroxy-carbamate in an aqueous methanol solution, were used as an equivalent of N -(/iocprotected nitrones in the nucleophilic addition of Grignard reagents (Scheme 2.144) (571). 

On the basis of the methylmagnesium bromide addition reaction to nitrones, an improved synthetic method of fluorinated tert-butyl amines was accomplished (Scheme 2.146) (573). 

Nucleophilic addition of methyl- or phenylphosphite n -butyl- esters to oxo-imine salts, generated by nitrone alkylation of triethyloxoniumtetrafluoro borate (Meerwein salt), leads to a-aminophosphinic acid esters (Scheme 2.201) (691). 

Regio- and stereospecific 1,3-cycloaddition of di-tert-butylated acyl nitrone (548), generated in situ from (547), with Z-2-cyclodecanone and subsequent aromatization is the key step in the synthesis of biomimetic pyridomacrolidin... 

Durand G, Polidori A, Puccio B. Nouveaux Derives Amphiphiles de L Alpha-C-Phenyl-N-tert-Butyl Nitrone, French Patent No. 2846968, May 14, 2004. 

Special spin-trapping techniques are also available for the detection of short-lived radicals in both homogeneous and heterogeneous systems. For instance, a-phenyl A-ferf-butyl nitrone (PBN), ferf-nitrosobutanc (f-NB), -(4-pyridyl A-oxidc) A-ferf-butyl nitrone (4-POBN), or 5,5-dimethyl-l-pyrroline A-oxidc (DMPO) can be made to react with catalytic intermediates to form stable paramagnetic adducts detectable by ESR [135], Radicals evolving into the gas phase can also be trapped directly by condensation or by using matrix isolation techniques [139],... 

In order to identify organic free - radicals present at quantifiable concentrations during the sonication of PCBs, we employed Electron Spin Resonance (ESR) with a spin trap, N-t-butyl-a-phenyl-nitrone (PBN). PBN reacts with the reactive free - radicals to form more stable spin-adducts, which are then detected by ESR. The ESR spectrum of a PBN spin adduct exhibits hyperfine coupling of the unpaired election with the 14N and the (3-H nuclei which leads to a triplet of doublets. The combination of the spin-adduct peak position and peak interval uniquely identifies the structure of a free-radical. 

The last few years have seen numerous applications of spin trapping to biological systems, and in these the trapping of hydroxyl radicals has assumed some importance. This work has been confined almost exclusively to nitrone scavengers 4 the fact that the hydroxyl adduct [6] of DMPO is much more persistent than that [7] of the commonly used nitrone, benzylidene-t-butylamine-N-oxide ( phenyl t-butyl nitrone ,3 or PBN) [3], may be due to a fragmentation reaction, with subsequent oxidation of the cr-hydroxybenzyl radical, as shown. 

The report by Lai and Piette (1979) that the radical detected in experiments with Fenton s reagent and MNP is t-butyl hydroxy nitroxide has now been shown to be in error (Kalyanaraman et al., 1979). The splitting parameters correspond with those of Bu NHO . It was also shown that this reduction of MNP could be effected by rat-liver microsomes in the presence of NADPH. A spectrum reasonably assigned to the hydroxyl adduct of MNP has been detected in radiolysis experiments (Sargent and Gardy, 1976) s An unsystematic nomenclature for nitrones has been adopted in this work... 

On occasion, nitrones may lead to unexpected nitroxides. Thus PBN is oxidized to benzoyl t-butyl nitroxide by NOz (Janzen and Blackburn, 1969 ... 

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