Selective cross-dehydrogenative C–O coupling of N-hydroxy compounds with pyrazolones. Introduction of the diacetyliminoxyl radical into the practice of organic synthesis. Issue 10 (26th July 2017)

• Record Type: Journal Article
• Authors: Krylov, Igor B.; Paveliev, Stanislav A.; Shelimov, Boris N.; Lokshin, Boris V.; Garbuzova, Irina A.; Tafeenko, Viktor A.; Chernyshev, Vladimir V.; Budnikov, Alexander S.; Nikishin, Gennady I.; Terent'ev, Alexander O.
• Is Part Of: Organic chemistry frontiers. Volume 4:Issue 10(2017)
• Page Start: 1947
• Page End: 1957
• Publication Date: 2017-07-26
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/c7qo00447h
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : Oxidative C–O coupling of oximes, N -hydroxyphthalimide, and N -hydroxybenzotriazole with pyrazolones via formation of N -oxyl radicals is described. 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 )2 Ce(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.