Purines. XXXI. : An X-Ray Crystallographic Structure Analysis of 3-Methyladenosine p-Toluenesulfonate

The X-ray crystal structure of the title compound (3·TsOH) has been determined. In the crystal, this salt has the exocyclic iminium structure (type 5). The adenine moiety is almost planar, and the N(9)-C(1') bond is almost coplanar with the adenine ring. However, the N(3)-methyl group is displaced rather significantly from planarity, and the endocyclic and exocyclic angles at N(3), C(4), and N(9) notably depart from those of the usual adenosine systems. The ribose moiety is in the C(2')-endo puckering conformation and in the high-anti conformation [with the torsion angle O(1')-C(1')-N(9)-C(4), x=-72.3°] with respect to the adenine moiety.