Synthesis of 2-(2-hydroxyethyl)-1-(2-hydroxyphenyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline and pseudosymmetry in its crystal structure.

Natural and synthetic isoquinoline alkaloids display a wide variety of potent biological activities. The title 1-aryl-2-hydroxyethyl-1,2,3,4-tetrahydroisoquinoline, C19H23NO4, crystallizes with two molecules in the asymmetric unit related by pseudo-translation but differing only slightly in conformation. The pseudosymmetry is also reflected in the diffraction pattern. The subset of reflections corresponding to the smaller cell and average structure are on average twice as intense as those subtending the larger cell. Tentative refinement in the subcell leads to a disordered structural model with satisfactory agreement factors and, after appropriate use of restraints, acceptable molecular geometry but significantly larger and more anisotropic displacement parameters. In the correct unit cell, the independent molecules differ with respect to the orientation of the hydroxyethyl group. Intramolecular hydrogen bonding occurs between the hydroxyphenyl group and the N atom.