Computer-Assisted 3D Structure Elucidation (CASE-3D) of Natural Products Combining Isotropic and Anisotropic NMR Parameters

A computer-assisted structural elucidation
(CASE-3D) strategy based
on the use of isotropic and/or anisotropic NMR data is proposed to
elucidate relative configuration and preferred conformation in complex
natural products. The methodology involves the selection of conformational
models through the use of the Akaike Information Criterion and scoring
of the different configurations. As illustrative examples, the methodology
furnished the correct configuration of the already known compounds
artemisinin (1) and homodimericin A (2).
Revised structures (5 and 6), including
their absolute configuration, for the recently reported curcusones
I (3) and J (4) are proposed.