Event Information
Progress Toward the Asymmetric Total Synthesis of the Marine Cyanobacterial Cyclodepsipeptide Apratoxin D
- Abstract:
Apratoxin D, recently isolated from /Lyngbya/ spp. of cyanobacteria, has potent cytotoxic effects against H-460 human lung cancer cells (IC_50 = 2.6 nM). A 25-membered cyclodepsipeptide, it consists of a polypeptide domain coupled to a novel polyketide domain, 3,7-dihydroxy-2,5,8,10,10-pentamethylundecanoic acid, via proline ester and thiazoline moieties. We have begun an asymmetric total synthesis of apratoxin D, employing alkylation of a chiral /N/-amino cyclic carbamate hydrazone as a key strategy for controlling the C37 and C39 polyketide stereocenters. A late stage intermediate of the polyketide domain, the /N/-Boc-L-proline ester of (3R,5S,6S)-5-hydroxy-3,6,8,8-tetramethylnonanal, has been successfully synthesized to date.
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