The total synthesis of (+)-elaeokanidine A: natural product or isolation artefact?

摘要

The first total synthesis of (+)-elaeokanidine A is reported. The synthesis features a formic acid-mediated cyclisation to access the indolizidine core and a double conjugate addition of ammonia to construct the piperidone unit. On the basis of H-1 NMR spectroscopic data, the relative stereochemistry of elaeokanidine A has been confirmed. Two isomeric species were also formed during the piperidone ring construction, which are potentially elaeokanidines B and C, although their structures could not be assigned unambiguously. The synthetic transformations used to prepare these products are analogous to conditions employed during the extraction procedure, raising questions about the true origins of these compounds. (C) 2014 Elsevier Ltd. All rights reserved.