Total synthesis of brevetoxin B.
The convergent total synthesis of brevetoxin B (1) has been achieved. The intramolecular allylation of the O,S-acetal 20, prepared from the alpha-chlorosulfide 17 and the alcohol 5, was carried out using AgOTf as a Lewis acid to give the diene 21, predominantly. Ring-closing metathesis of 21 with the Grubbs catalyst 23 afforded the hexacyclic ether 25 which was converted to the A-G ring segment 2 through several steps. The intramolecular allylation of the alpha-acetoxy ether 42, prepared from 2 and the J-K ring segment 3, followed by ring-closing metathesis provided the polycyclic ether framework 44. A series of reactions of 44, including oxidation of the A ring, deprotection of the silyl ethers, and selective oxidation of the resulting allylic alcohol, furnished 1.
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
Takamura
Hiroyoshi
H
Nishii
Hiroki
H
Yamamoto
Yoshinori
Y
D008387:Marine Toxins / Q000138:chemical synthesis*; D008968:Molecular Conformation; D035964:Oxocins / Q000138:chemical synthesis*; D013237:Stereoisomerism; D000095702:Polyether Toxins
D008387:Marine Toxins; D035964:Oxocins; C043466:brevetoxin B; D000095702:Polyether Toxins