Structure of aristone, a unique indole alkaloid from Aristotelia chilensis(mol.) stuntz, by X-ray crystallographic analysis

Abstract

Aristone, aristoteline, aristotelinine, and aristotelone were isolated from Aristotelia chilensis and belong to a unique class of alkaloids found only in the genus Aristotelia. The structure of aristone was determined by X-ray diffraction techniques. Crystals are orthorhombic, space group P2₁2₁2₁, with cell dimensions a= 11.075(3), b= 18.004(4), and c= 7.973(1)Å and Z= 4. The crystal structure was determined by direct methods and atomic positional and thermal parameters were refined by full-matrix least-squares techniques to a R value of 3.8% utilizing 1 717 reflexions. The molecule contains a planar indole moiety with the remainder of the molecule forming a basket-like cavity. There are a number of carbon valence angles less than 105° which indicate internal strain; however, there are no significant intramolecular interactions.