Xestoproxamines A–C from Neopetrosiaproxima. Assignment of Absolute Stereostructure ofbis-Piperidine Alkaloids by Integrated Degradation-CDAnalysis

摘要

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 stereo-heterogeneity – and tertiary cyclic amines in general.