Publication at Faculty of Science |
2008
Abstract
Treatment of 9- or 7-substituted 6-, 2-, or 8-iodopurine derivatives with copper(I) thiophene-2-carboxylate or copper(I) 3-methylsalicylate in N,N-dimethylformamide affords the corresponding 6,6′-, 2,2′-, and 8,8′-purine dimers in high yield. Cross-dimerization reactions of different iodo derivatives were attempted, but only mixtures containing the cross-coupled products, homodimers, or dehalogenation products were obtained.
The crystal structures of 9,9′-dibenzyl- (1a) and 9,9′-bis(1-methylethyl)-9H,9′H-[6,6′]bipurinyl (1c) and the salt [1aH2]Br2 were determined by single-crystal X-ray diffraction analysis, which revealed extensive hydrogen bonding and π···π stacking interactions.