Chiral N-hydroxybenzamides (1H–3H) have been synthesized as precursors of chiral short-lived N-oxyl radicals 1•–3•. The latter species have been generated by oxidation of 1H–3H with Pb(OAc)4 or hydrogen abstraction from 1H–3H by the tert-butoxyl radical and characterized by UV–vis spectrophotometry and EPR spectroscopy. Through a kinetic study of the hydrogen atom transfer processes promoted by 1•–3• from three chiral benzylic substrates (1-phenylethylamine, 1-phenylethanol, and α-vinylbenzyl alcohol), a moderate chiral discrimination has been found, with selectivity factors 0.5 ≤ kH(S)/kH(R) ≤ 2.
ChiralN-Hydroxybenzamides as Potential Catalysts for Aerobic Asymmetric Oxidations / Maria Grazia Capraro;Paola Franchi;Osvaldo Lanzalunga;Andrea Lapi;Marco Lucarini. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 79:(2014), pp. 6435-6443. [10.1021/jo500844c]
ChiralN-Hydroxybenzamides as Potential Catalysts for Aerobic Asymmetric Oxidations
FRANCHI, PAOLA;LUCARINI, MARCO
2014
Abstract
Chiral N-hydroxybenzamides (1H–3H) have been synthesized as precursors of chiral short-lived N-oxyl radicals 1•–3•. The latter species have been generated by oxidation of 1H–3H with Pb(OAc)4 or hydrogen abstraction from 1H–3H by the tert-butoxyl radical and characterized by UV–vis spectrophotometry and EPR spectroscopy. Through a kinetic study of the hydrogen atom transfer processes promoted by 1•–3• from three chiral benzylic substrates (1-phenylethylamine, 1-phenylethanol, and α-vinylbenzyl alcohol), a moderate chiral discrimination has been found, with selectivity factors 0.5 ≤ kH(S)/kH(R) ≤ 2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
