Madangamines are a small group of complex pentacyclic alkaloids isolated from marine sponges of the order Haplosclerida, biogenetically derived from partially reduced bis-3-alkylpyridine macrocycles. Madangamine A, isolated from Xestospongia ingens by Andersen and co-workers in 1994  was the first example of this new class of pentacyclic alkaloids and showed significant in vitro cytotoxicity against a number of cancer cell lines. Soon afterwards, four new members of this group, madangamines B–E, were isolated from the same sponge  and more recently madangamine F, also showing cytotoxic activity, has been isolated from the marine sponge Pachychalina alcaloidifera .
For the first time, the diazatricyclic core common to all madangamines has been enantioselectively assembled by M. Amat, J. Bosch and colleagues from the University of Barcelona, Spain. This represents a significant breakthrough in the total synthesis of these natural products. The key steps involve a stereoselective conjugate addition, ring-closing metathesis, stereoselective generation of the C–9 stereocenter, and closure of the piperidine A ring by aminohydroxylation.
- First Enantioselective Synthesis of the Diazatricyclic Core of Madangamine Alkaloids
M. Amat, M. Pérez, S. Proto, T. Gatti, J. Bosch,
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