Nitroxides. XIX. Norpseudopelletierine-N-oxyl, a New, Stable, Unhindered Free Radical

Aerobic oxidation catalysis with stable radicals

“…Recently the use of sterically unhindered nitroxyl radicals has emerged. Such radicals have been known since the 1960s 14 but until recently they have not been exploited for oxidation catalysis. Unlike TEMPO, unhindered radicals such as those shown in Fig.…”

Aerobic oxidation and oxidative esterification of alcohols through cooperative catalysis under metal-free conditions

“…Prepared through a three-step synthetic route, the radical ABNO is an economically viable nitroxyl radical bearing hydrogen atoms on the α-carbons (avoiding to violate Bredt's rule) alternative to AZADO. 8 Known since the mid-1960s, 9 such less-hindered nitroxyl radicals mediate the oxidation of sterically hindered alcohols for which TEMPO is not a suitable catalyst. Applications include the efficient oxidation of chiral alcohols using chirally modified AZADOs, 10 as well as 9-azanoradamantane N-oxyl (Nor-AZADO) exhibiting higher catalytic activity than AZADO, ABNO and TEMPO.…”

N-tert-butylmethanimine N-oxide is an efficient spin-trapping probe for EPR analysis of glutathione thiyl radical

“…1, denoted in red and blue color, respectively) tend to form nitroxides with more resolved EPR spectra than their acyclic analogues4 and that hindrance of the nitroxide group stabilizes678 spin-adducts while polarization of the N-Cα bond destabilizes them910. The sensitivity of the spin-trapping technique is negatively affected by the dismutation of α-H spin-adducts to nitrones and hydroxylamines811, whereas analyses in biological matrices are further complicated by the propensity of nitroxides to undergo one-electron reduction or oxidation either to “EPR-silent” hydroxylamines or to oxoammonium salts121314. The short half-lives of most spin-adducts necessitate the performance of analyses under steady-state conditions in which radical species are generated at considerable rates.…”