Xestoproxamines A-C from Neopetrosia proxima. Assignment of Absolute Stereostructure of Bis-piperidine Alkaloids by Integrated Degradation-CD Analysis

The complete stereostructures of xestoproxamines A-C, from the Bahamian sponge Neopetrosia proxima, were assigned from spectroscopic analysis, including MS, 2D NMR, and integrated degradation-CD analysis. Two new CD application protocols are described for defining absolute configuration: one for allylic methyl groups in branched chains and a second for the heterocyclic core bis-piperidine with Specific applicability to other members of this class alkaloids-known for their stereoheterogeneity-and tertiary cyclic amines in general.