Hydrogen bonding of modified bases involving Watson‐Crick sites: Crystal structure and conformation of Benzyl 6‐aminopurine‐7‐carboxylate

Crystals of benzyl 6-aminopurine-7-carboxylate (C13H11N5O2) are monoclinic, space group C2/c, Z = 8, with a = 25.448 (9), b = 6.052 (1), c = 16.975 (6)A, β = 112.05 (5)°, M = 269.27, Dm= 1.49, Dx= 1.48 g/cm3. The structure was determined from three-dimensional diffractometric data by the multisolution technique and refined to a final reliability factor of 0.068. The molecule is planar with an intramolecular hydrogen bond from one of the amino hydrogens, Ha(N6) to the keto oxygen O(10) of the acyl group. The molecules are hydrogen bonded across the center of inversion by a pair of intermolecular hydrogen bonds using the Watson-Crick sites. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)