Selective cross-dehydrogenative C–O coupling of N-hydroxy compounds with pyrazolones. Introduction of the diacetyliminoxyl radical into the practice of organic synthesis†,10.1039/C7QO00447H

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Lactoyl-CoA 全氟丁基戊烷白叶藤碱全氟己基辛烷新白叶藤碱壳寡糖特色专题-生物多肽

Selective cross-dehydrogenative C–O coupling of N-hydroxy compounds with pyrazolones. Introduction of the diacetyliminoxyl radical into the practice of organic synthesis†

Igor B. Krylov,Stanislav A. Paveliev,Boris N. Shelimov,Boris V. Lokshin,Irina A. Garbuzova,Viktor A. Tafeenko,Gennady I. Nikishin,Alexander O. Terent'ev

Organic Chemistry Frontiers Pub Date : 07/18/2017 00:00:00 , DOI:10.1039/C7QO00447H

Abstract

Oxidative C–O coupling of pyrazolones with N-hydroxy compounds of different classes (N-hydroxyphthalimide, N-hydroxybenzotriazole, oximes) was achieved; both one-electron oxidants (Fe(ClO₄)₃, (NH₄)₂Ce(NO₃)₆) and two-electron oxidants (PhI(OAc)₂, Pb(OAc)₄) are applicable, and the yields reach 91%. Apparently, the coupling proceeds via the formation of N-oxyl radicals from N-hydroxy compounds. One of the N-oxyl intermediates, the diacetyliminoxyl radical, was found to be exclusively stable in solution in spite of being sterically unhindered; it was isolated from an oxidant and used as a new reagent for the synthesis and mechanism study. The products of C–O coupling of pyrazolones with N-hydroxyphthalimide can be easily transformed into aminooxy compounds, valuable substances for combinatorial chemistry.