Hydrogen-bonded DeUG x DAN heterocomplex: structure and stability and a scalable synthesis of DeUG with reactive functionality.

A convenient, scalable synthesis of the supramolecular building block 7-deazaguanine-based urea (DeUG) is reported. Incorporation of reactive moieties (DeUG azide 10 and alkyne 11 for copper-catalyzed azide-alkyne cycloadditions, "click chemistry") and a demonstration of transesterification (DeUG glycol, 12) highlights the versatility. X-ray structures of DeUG and a DeUG x DAN heterocomplex were obtained. K(assoc) for the 1.2 heterocomplex was estimated to be 2 x 10(8) M(-1) in chloroform.