Cobalt-mediated radical coupling (CMRC): an unusual route to midchain-functionalized symmetrical macromolecules.
Cobalt-mediated radical coupling (CMRC) is a straightforward approach to the synthesis of symmetrical macromolecules that relies on the addition of 1,3-diene compounds onto polymer precursors preformed by cobalt-mediated radical polymerization (CMRP). Mechanistic features that make this process so efficient for radical polymer coupling are reported here. The mechanism was established on the basis of NMR spectroscopy and MALDI-MS analyses of the coupling product and corroborated by DFT calculations. A key feature of CMRC is the preferential insertion of two diene units in the middle of the chain of the coupling product mainly according to a trans-1,4-addition pathway. The large tolerance of CMRC towards the diene structure is demonstrated and the impact of this new coupling method on macromolecular engineering is discussed, especially for midchain functionalization of polymers. It is worth noting that the interest in CMRC goes beyond the field of polymer chemistry, since it constitutes a novel carbon-carbon bond formation method that could be applied to small organic molecules.
Debuigne
Antoine
A
Center for Education and Research on Macromolecules, University of Liège, Sart-Tilman, B6a, 4000 Liège, Belgium. adebuigne@ulg.ac.be
Poli
Rinaldo
R
De Winter
Julien
J
Laurent
Pascal
P
Gerbaux
Pascal
P
Dubois
Philippe
P
Wathelet
Jean-Paul
JP
Jérôme
Christine
C
Detrembleur
Christophe
C