Strong Dimerization of Ureidopyrimidones via Quadruple Hydrogen Bonding

Abstract

6-Methyl-2-butylureidopyrimidone dimerizes via four hydrogen bonds in the solid state as well as in CHCl3 solution via a donor−donor−acceptor−acceptor (DDAA) array of hydrogen bonding sites in the 4[1H]-pyrimidinone tautomer. An intramolecular hydrogen bond from the pyrimidine NH group to the urea oxygen atom preorganizes the molecules for dimerization. The dimerization constant of the dimer in CHCl3 exceeds 106 M-1. In CHCl3 containing DMSO, the dimer is in equilibrium with the monomeric 6[1H]-pyrimidinone tautomer. In 6-phenyl-2-butylureidopyrimidone, the 4[1H]-pyrimidinone tautomer coexists with the pyrimidin-4-ol form, which dimerizes with similar high dimerization constants via four hydrogen bonds in a DADA array. The latter tautomer predominates in derivatives with electronegative 6-substituents, like 6-nitrophenyl- and 6-trifluoromethyl-2-butylureidopyrimidone. Due to its simple preparation and high dimerization constant, the ureidopyrimidone functionality is a useful building block for supramolecular chemistry.

Crystal structure of N-phenyl-2-(pyridin-4-ylcarbonyl)hydrazinecarboxamide with Z′ = 4, C13H12N4O2

“…These molecules have also received much attention as fundamental synthetic building blocks because of their hydrogen bonding and π-π stacking potential. In particular, Meijer's ureidopyrimidone (UPy) building block [9,10], with its characteristics of a high dimerization constant and synthetic accessibility, has found widespread applications in supramolecular chemistry, materials science, and catalysis [11,12]. Zimmerman's ureidodeazapterin and ureidonaphthyridine modules are also successful examples of heterocyclic building blocks [13][14][15][16].…”

Polystyrene supramolecular networks based on DA-AD hydrogen bonds

“…[24][25][26][27] Polymers with double hydrogen bonds based on amides could be achieved by radical copolymerizations [28][29][30][31] or polycondensation. [32] These copolymers have a good water solubility due to the amide groups and the strength of intermolecular hydrogen bonds which have been qualitatively [28] or quantitatively [32] studied by NMR at different temperatures.…”

Photoinduced Electron Transfer within Porphyrin‐Anthra‐quinone Dyads Connected by Hamilton Hydrogen Bonding

“…Sessler et al 12,13 developed a non-covalently assembled supramolecular system based on Watson-Crick-type nucleic acid base pairing interactions, and the hydrogen bonds provided an effective pathway for mediating the electron transfer process. The 2-ureido-4[1H]-pyrimidinone motif reported by Meijer et al 14 represents a fascinating self-complementary quadruple hydrogen bonding module and Tung et al 15 have shown that the triplet energy transfer can occur via a 'through bond' mechanism in this system. Our research group also provided an example that the hydrogen bonding and salt-bridges can mediate the triplet energy transfer.…”