Document Type

Article

Publication Date

10-24-2019

Publication Source

Tetrahedron Letters

Volume Number

60

Issue Number

43

Publisher

Elsevier

ISSN

0040-4039

Article Number

151193

Comments

Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND)

Anna M. Bauer, Erin E. Ramey, Kjersti G. Oberle, Gretchen A. Fata, Chloe D. Hutchison, Christopher R. Turlington, Cross-linked poly(4-vinylpyridine-N-oxide) as a polymer-supported oxygen atom transfer reagent, Tetrahedron Letters, Volume 60, Issue 43, 2019, 151193, ISSN 0040-4039, https://doi.org/10.1016/j.tetlet.2019.151193

Abstract

Oxygen atom transfer (OAT) reagents are common in biological and industrial oxidation reactions. While many heterogeneous catalysts have been utilized in OAT reactions, heterogeneous OAT reagents have not been explored. Here, cross-linked poly(4-vinylpyridine-N-oxide), called x-PVP-N-oxide, was tested as a heterogeneous OAT reagent and its oxidation chemistry compared to its molecular counterpart, pyridine-N-oxide. The insoluble oxidant x-PVP-N-oxide demonstrated comparable reactivity to pyridine-N-oxide in direct oxidation reactions of phosphines and phosphites in acetonitrile, but x-PVP-N-oxide did not react in other solvents. The polymer backbone of x-PVP-N-oxide, however, allowed for easy filtering and recycling in sequential oxidation reactions. In addition, x-PVP-N-oxide was tested as the stoichiometric oxidant in a copper-catalyzed OAT reaction to α-diazo-benzeneacetic acid methyl ester. The heterogeneous oxidant was much less reactive than pyridine-N-oxide, indicating that interaction with the metal catalyst was challenging. These results demonstrated a proof-of-concept that recyclable, polymer-supported OAT reagents could be a viable OAT reagents in direct oxidation reactions without metal catalysts.

Keywords

Oxygen atom transfer, N-Oxide, Recyclable, Polymer-supported

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