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. © 2014 American Chemical Society.
Chiral N-hydroxybenzamides as potential catalysts for aerobic asymmetric oxidations / Maria Grazia, Capraro; Paola, Franchi; Lanzalunga, Osvaldo; Lapi, Andrea; Marco, Lucarini. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 79:14(2014), pp. 6435-6443. [10.1021/jo500844c]
Chiral N-hydroxybenzamides as potential catalysts for aerobic asymmetric oxidations
LANZALUNGA, Osvaldo;LAPI, Andrea;
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. © 2014 American Chemical Society.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
