A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Brønsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies
基于路易斯碱/布朗斯台德酸共催化的均烯丙基酸的硫醇化反应,开发了一种简便制备各种对映体富集的苯硫基取代的内酯的策略。探索了酸控制的区域发散环化(6-endo vs. 5-exo)和苯硫基取代的内酯的酸介导的立体选择性重排。进行了实验和计算研究以阐明区域选择性和对映选择性的起源。计算结果表明,CO和CS键的形成可能会同时发生,而不会形成通常认为的催化剂配位的硫鎓离子中间体,而且底物和SPh之间的潜在π-π堆积是对映确定步骤的重要因素。最后,
Total Synthesis and Preliminary Biological Evaluation of <i>cis</i>-Solamin Isomers
作者:Alex R. L. Cecil、Yulai Hu、María J. Vicent、Ruth Duncan、Richard C. D. Brown
DOI:10.1021/jo049909g
日期:2004.5.1
An efficient totalsynthesis of cis-solamin (1) has been achieved in 21% overall yield and with a longest linear sequence of just 11 steps from aldehyde 8. A key feature of the approach was the use of asymmetric permanganate-promoted oxidative cyclization to introduce four of the five required stereocenters in a single step. The use of robust and chemoselective methodology meant that the use of protecting
A general synthetic route towards γ- and δ-lactones. Total asymmetric synthesis of (−)-muricatacin and the mosquito oviposition pheromone (5R,6S)-6-acetoxy-hexadecanolide
作者:Elias A. Couladouros、Anastasia P. Mihou
DOI:10.1016/s0040-4039(99)00895-3
日期:1999.6
Five (or six) membered asymmetric lactones are synthesized from γ-butyrolactone (or δ-valerolactone) in a straightforward way using the following reaction sequence: reduction, Wittig-Schlosser coupling, Sharpless asymmetric dihydroxylation, oxidation and lactonization. Thus, (−)-muricatacin is synthesized in six steps (43 % overall yield). Furthermore, (5R,6s)-6-acetoxy-hexadecanolide is prepared in
Synthesis of <i>cis-</i>Solamin Using a Permanganate-Mediated Oxidative Cyclization
作者:Alexander R. L. Cecil、Richard C. D. Brown
DOI:10.1021/ol026669n
日期:2002.10.1
[GRAPHICS]cis-Solamin (1) and its diastereoisomer 14 have been synthesized in 13 steps using the diastereoselective permanganate-promoted oxidative cyclization of 1,5-dienes to create the tetrahydrofuran diol core. Notably, no protecting groups are required during the stages of fragment assembly.