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The Mechanism of Ureido-Pyrimidinone:2,7-Diamido-Naphthyridine Complexation and the Presence of Kinetically Controlled Pathways in Multicomponent Hydrogen-Bonded Systems

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journal contribution
posted on 23.04.2008, 00:00 by Tom F. A. de Greef, G. B. W. L. Ligthart, Martin Lutz, Anthony L. Spek, E. W. Meijer, Rint P. Sijbesma
The kinetics of association of ureido-pyrimidinone (U) dimers, present either in the 4[1H]-keto form or in the pyrimidin-4-ol form, with 2,7-diamido-1,8-naphthyridine (N) into a complementary heterodimer have been investigated. The formation of heterodimers with 2,7-diamido-1,8-naphthyridine from pyrimidin-4-ol dimers is much faster than from 4[1H]-pyrimidinone dimers. Using a combination of simple measurements and simulations, evidence for a bimolecular tautomerization step is presented. Finally, the acquired kinetic knowledge of the different pathways leading from ureido-pyrimidinone homodimers to ureido-pyrimidinone:diamido-naphthyridine (U:N) heterodimers allows the prediction and observation of kinetically determined ureido-pyrimidinone heterodimers which slowly convert back to the corresponding homodimers.