Crystal and molecular structure of augustamine

The crystal and molecular structure of augustamine (1), C17H19NO4, an amary llidaceae alkaloid of the tazettine group has been determined by direct met hods from single crystal x-ray diffractometer data and refined by full-matr ix least squares. The alkaloid (1) crystallizes in the space group P2(1)2(1 )2(1), with cell parameters: a = 7.833(8) b = 11.08(2) (a) over circle, c = 16.69(6) Angstrom, Z = 4, D-c =1.381 g/cm(-3), R = 7.6% for 1115 observed reflections. The molecule, having a hexacyclic ring system, is very rigid w ith the ring B in a chair conformation. Molecular mechanics calculations ha ve been made using MM3(2000) force field.