Highly diastereoselective 7-endo radical cyclization of ethyl α-methylene-γ-(bromomethyl)dimethylsiloxycarboxylates
作者:Hajime Nagano、Saori Hara
DOI:10.1016/j.tetlet.2004.03.188
日期:2004.5
The 7-endo radical cyclization of (bromomethyl)dimethylsilyl ethers derived from ethyl gamma-hydroxy-alpha-methylenecarboxylates bearing a bulky gamma-substituent such as isopropyl, cyclohexyl, and tert-butyl groups in tetrahydrofuran gave preferentially cyclic silyl ethers bearing the ethoxycarbonyl group anti to the gamma-substituents in high yields. Treatment of the cyclic silyl ethers with silica gel gave acyclic ethyl gamma-hydroxy-alpha-[2-(hydroxydimethylsilyl)ethyl]carboxylates. The reduction of the cyclization products with DIBAL followed by Tamao oxidation gave the corresponding acyclic triols. (C) 2004 Elsevier Ltd. All rights reserved.
Total synthesis of palmyrolide A and its 5,7-epi isomers
Stereoselective total synthesis of palmyrolide A, a 15-membered neuroactive macrolide, was described by adopting a synthetic strategy developed for the proposed structures, and its 5,7-epi isomers. The strategy was designed in such a way that the set of stereoisomers, which were needed for establishing the absolute configuration of palmyrolide A, could be obtained from one time operation. The diastereoselective