The structure of cascarillin: X-ray analysis of deacetylcascarillin acetal iodoacetate

Abstract

X-Ray crystal-structure analysis of deacetylcascarillin acetal iodoacetate has established the constitution and absolute stereochemistry of cascarillin, the diterpenoid bitter principle of cascarilla bark. Crystals of the iodoacetate are orthorhombic, of space group P2₁2₁2₁, with four molecules of C₂₂H₂₉IO₆ in a unit cell of dimensions a= 13·46, b= 21·26, c= 7·80 Å. Phase determination was based initially on the iodine atom, and Fourier and least-squares methods were used for the determination of the atomic parameters. The final value of the discrepancy R over 964 independent reflexions is 18·5%.