CRYSTAL AND MOLECULAR-STRUCTURE OF DELSOLINE

The crystal and molecular structure of the diterpenoid alkaloid delsoline (1) C25H41NO7, M(r)467.61, has been determined by an X-ray analysis. The X-ray crystal structure which could not be solved earlier with MULTAN, has now been solved using the SIR 88 analysis program. The compound crystallizes in the space group P2(1)2(1)2, with cell parameters: a = 12.529(2), b = 13.118(1), c = 14.231(6) angstrom, V = 23 39(1) angstrom3, Z = 4, D(calc) = 1.33 g/cm-3, lambda(Cu Kalpha) = 1.54184 angstrom, mu(Cu Kalpha) = 7.4 cm-1, R/R(w) = 0.068/0.040 for 2539 reflections. The A ring of delsoline exists in the boat conformation stabilized by an intramolecular N --- H-O hydrogen bond. Ring D also is in a boat form. Unambiguous proton and carbon-13 nmr assignments have been made by a detailed analysis of the DEPT, COSY, NOESY, and HETCOR nmr spectra.