Molecular structure and absolute stereochemistry of a 1-phenylethylisoquinoline alkaloid from Colchicum cornigerum: X-ray analysis of a methiodide derivative

Abstract

The alkaloid CC-2 (Colchicum cornigerum alkaloid number 2) has been shown to possess the molecular structure and absolute stereochemistry (I) by single-crystal X-ray analysis of a methiodide derivative. Crystals are orthorhombic, space group P2₁2₁2₁, with Z= 4 in a unit cell of dimensions a= 7·75(2), b= 14·57(2), c= 21·55(4)Å. The structure was solved by the heavy-atom method by use of 1739 visually estimated independent reflexions, and refined by block-diagonal least-squares calculations to R 0·13. The absolute configuration was determined by considering anomalous scattering effects.