Improved synthesis of the A-G ring segment of brevetoxin B.
An efficient synthesis of the A-G ring segment 2, a key intermediate for the total synthesis of brevetoxin B (1), was achieved in 37 steps and 5.0% overall yield. The intramolecular allylation of the O,S-acetal 22, prepared from the ABC ring segment 15 and the FG ring segment 17, was carried out using AgOTf as a Lewis acid to give the desired compound 23, predominantly. Ring-closing metathesis of 23 with the Grubbs catalyst 12 afforded the heptacyclic ether 25. Selective hydrogenation of the E ring olefin of 25 was performed by diimide reduction to afford 2.
Kadota
Isao
I
Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan. ikadota@mail.tains.tohoku.ac.jp
Nishii
Hiroki
H
Ishioka
Hiroki
H
Takamura
Hiroyoshi
H
Yamamoto
Yoshinori
Y
D008387:Marine Toxins / Q000138:chemical synthesis*; D015394:Molecular Structure; D035964:Oxocins / Q000138:chemical synthesis*; D000095702:Polyether Toxins
D008387:Marine Toxins; D035964:Oxocins; C043466:brevetoxin B; D000095702:Polyether Toxins