Synthesis and mass spectrometric analysis of cyclostellettamines H, I, K and L

Very recently the new cyclostellettamines H, I, K and L were identified from a Brazilian sponge of the genus Pachychalina. They were isolated together with the known cyclostellettamines A-G in a mixture of only 1.5 mg. To obtain further material for biological investigations, the synthesis of the four new cyclostellettamines has been carried out. Since mass spectrometry plays an essential role in identifying these compounds a systematic analysis of the cyclostellettamines is discussed. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).