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.