Crystal and molecular structure of delsoline

Abstract

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 withMultan, has now been solved using the SIR 88 analysis program. The compound crystallizes in the space groupP2₁2₁2₁ with cell parameters:a=12.529(2),b=13.118(1),c=14.231(6)Å,V=2339(1)ų,Z=4,D _calc=1.33 g/cm^-3, λ(Cu Kα)=1.54184 Å,μ(Cu Kα)=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.