Synthetic studies on palytoxin stereocontrolled practical synthesis of the C.85 – C.98 segment

✍ Scribed by W.W. McWhorter Jr.; S.H. Kang; Y. Kishi

• Publisher: Elsevier Science
• Year: 1983
• Tongue: French
• Weight: 184 KB
• Volume: 24
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)81894-8

✦ Synopsis

A stereocontrolled 12-step synthesis of the C.85-C.98 segment of palytoxin is described, Recent work in this laboratory has established the complete structure and laid a solid foundation for the chemical synthesis of the structurally novel and highly physioloqically active marine natural product palytoxin. 2,3 Our synthetic plan calls for construction of the toxin from a series of segments containing multiple chiral centers which were chosen by key bond disconnections of the carbon backbone. For this communication, we would like to report a highly stereoselective and efficient synthesis of the C.85-C.98 segment.* The synthesis began with the a-allylpyranose l_, which was readily available from 2,3,4,6tetra-0-bensyl-D-glucopyranose in large quantities. 5 Osonolysis of I, followed by Wittig reaction using (i-Pr0)2P(0)CH2C02Et in the presence of t-BuOK, 6 gave the expected trans-ester' contaminated with less than 2% of the corresponding cis-ester. Diisobutylaluminum hydride (DIBAL) reduction of the ester yielded the trans-allylic alcohol2 [co +44.2O (c 1.56, CHC13)1