Intramolecular Radical CyclizationRing-Closing Metathesis Approach to Fused Polycyclic Ethers. Convergent Synthesis and Conformational Analysis of the (E)FGH Ring System of Ciguatoxin
作者:Makoto Sasaki、Tetsuji Noguchi、Kazuo Tachibana
DOI:10.1021/jo010974p
日期:2002.5.1
A convergent synthetic route to the (E)FGH ringsystem 4 of ciguatoxins, the causative toxins for ciguatera fish poisoning, has been developed. The synthesis features convergent coupling to form dioxane acetal, regioselective acetal cleavage by diethylaluminum phenylthiolate or diisobutylaluminum phenylselenolate followed by intramolecular radical cyclization to construct the oxepane ring G, and a
Does the wittig-still rearrangement proceed via a metal free carbanion?
作者:Birgit Kruse、Reinhard Brückner
DOI:10.1016/s0040-4039(00)97638-x
日期:1990.1
The steric course of [2,3] rearrangements of allyloxy methanides is almost not affected by the counterion (M = Li, Na, K, Rb, Cs) as demonstrated by the nearly metal independent E,Z and anti,syn selectivities of rearrangements 4 → 6 and 7 → 8, respectively.
A stereoselective synthesis of the EFGH ring fragment of ciguatoxin CTX3C has been achieved through: (i) selective cleavage of a dioxepane acetal CO bond; (ii) radical cyclization to form the oxepane G ring; and (iii) chemoselective ring-closing metathesis of a triene yielding the hexahydrooxonin F ring.
Synthesis of chiral 1,2-diols and related compounds of biological activities via stepwise ring fission of 5-alkyl-6,8-dioxabicyclo[3.2.1]octane skeleton
Stereoselective synthesis of the FGH ring fragment of ciguatoxin is described. The key steps in the present synthesis are an intramolecular radical cyclization to construct oxepane ring G and ring-closing metathesis reaction to construct hexahydrooxonin ring F. (C) 1999 Elsevier Science Ltd. All rights reserved.