Rapid, selective, and reversible nitroxide radical coupling (NRC) reactions at amibient temperature

Kulis, Jakov, Bell, Craig A., Micallef, Aaron S., Jia, Zhongfan and Monteiro, Michael J. (2009) Rapid, selective, and reversible nitroxide radical coupling (NRC) reactions at amibient temperature. Macromolecules, 42 21: 8218-8227. doi:10.1021/ma9014565

Author Kulis, Jakov
Bell, Craig A.
Micallef, Aaron S.
Jia, Zhongfan
Monteiro, Michael J.
Title Rapid, selective, and reversible nitroxide radical coupling (NRC) reactions at amibient temperature
Journal name Macromolecules   Check publisher's open access policy
ISSN 0024-9297
Publication date 2009-11-10
Year available 2009
Sub-type Article (original research)
DOI 10.1021/ma9014565
Volume 42
Issue 21
Start page 8218
End page 8227
Total pages 10
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Subject 0303 Macromolecular and Materials Chemistry
Formatted abstract
High activation of polystyrene with bromine end groups (PSTY-Br) to their incipient radicals occurred in the presence of Cu(I)Br, Me6TREN, and DMSO solvent. These radicals were then trapped by nitroxide species leading to coupling reactions between PSTY-Br and nitroxides that were ultrafast and selective in the presence of a diverse range of functional groups. The nitroxide radical coupling (NRC) reactions have the attributes of a “click” reaction with near quantitative yields of product formed, but through the reversibility of this reaction, it has the added advantage of permitting the exchange of chemical functionality on macromolecules. Conditions were chosen to facilitate the disproportionation of Cu(I)Br to the highly activating nascent Cu(0) and deactivating Cu(II)Br2 in the presence of DMSO solvent and Me6TREN ligand. NRC at room temperature gave near quantitative yields of macromolecular coupling of low molecular weight polystyrene with bromine chain-ends (PSTY-Br) and nitroxides in under 7 min even in the presence of functional groups (e.g., -Ξ , -OH, -COOH, -NH2, =O). Utilization of the reversibility of the NRC reaction at elevated temperatures allowed the exchange of chain-end groups with a variety of functional nitroxide derivatives. The robustness and orthogonality of this NRC reaction were further demonstrated using the Cu-catalyzed azide/alkyne “click” (CuAAC) reactions, in which yields greater than 95% were observed for coupling between PSTY-N3 and a PSTY chain first trapped with an alkyne functional TEMPO (PSTY-TEMPO-Ξ).     
Keyword Ring-opening Polymerization
Diels-alder Chemistry
One-pot Synthesis
Click Chemistry
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

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Created: Sun, 15 Nov 2009, 10:01:48 EST