8-Amino-7-(4-morpholinobutyl)theophylline

The crystal structure of the title compound, 8-amino-1,3-dimethyl-7-(4-morpholinobutyl)-3,7-dihydro-1H-purine-2,6-dione, C₁₅H₂₄N₆O₃, (III), is described and compared with that of 8-amino-7-(2-hydroxy-3-morpholinopropyl)theophylline, (I). The molecules of (III) have a typical geometry. In the purine fused-ring system the six-membered ring is planar to within 0.006 (2) Å, the five-membered ring is planar to within 0.011 (2) Å and they are inclined at 0.72 (8)°. The aminoalkyl side chain in the 7 position of the theophylline has a gauche-trans-gauche-gauche-gauche conformation and that conformation may be influenced by a weak N-H...N intramolecular hydrogen bond. The morpholine ring adopts a chair conformation with the puckering parameters Q = 0.560 (2) Å, [theta] = 178.5 (2)° [Cremer & Pople (1975). J. Am. Chem. Soc. 97, 1354-1358]. The molecules in the crystal are joined in chains parallel to [010] direction by an N-H...O intermolecular hydrogen bond. Inversion-related purine parts of the molecules overlap with each other, with the mean separation between molecular planes of 3.46 (1) Å.

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