Taumycins A (1) and B (2) were isolated in 2008 from the Madagascar Sponge Fascaplysinopsis sp. by Kashman and co-workers. Among these lipodepsipeptides, Taumycin A (1) was shown to inhibit the UT-7 leukemic cell line in the micro molar range. We became interested in this molecule, in part, because of its interesting biological profile but also due to its unique structural features: enantiomeric isoleucine residues and the unique side chain consisting of a methyl stereo center imbedded between two tri-substituted E olefins. By first targeting the Taumycin aldehyde, the relative configuration of the macrocycle was identified in 2014. With the known relative configuration in hand, we envision the total synthesis to proceed via a stereoselective aldol union of a pseudo-symmetrical side chain utilizing orthogonal protecting groups to access the two possible diastereomeric combinations of the desired natural product. The key step for the synthesis will be our already established thermal rearrangement of the a-keto tert-butyl ester.

Total synthesis of taumycins A and B

253rd National Meeting (2017)

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