Stereoselective synthesis of medium-sized cyclic ethers: Application of C-glycosylation chemistry to seven- to nine-membered lactone-derived thioacetals and their sulfone counterparts
Stereoselective synthesis of medium-sized cyclic ethers: Application of C-glycosylation chemistry to seven- to nine-membered lactone-derived thioacetals and their sulfone counterparts
复制标题
中等大小环醚的立体选择性合成：C-糖基化化学在七至九元内酯衍生的硫缩醛及其砜对应物中的应用
DOI：
10.1021/jo4025545
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Makoto Sasaki
中科院分区：
文献类型：
--
作者：
Yuto Suga;Haruhiko Fuwa;Makoto Sasaki
通过内酯硫代缩醛及其砜衍生物的亲核取代反应，实现了α，α′-取代中型环醚的立体选择性合成。通过（i）在烯丙基三甲基硅烷或TMSCN存在下用NIS/TMSOTf活化或通过（ii）氧化成相应的砜，然后用适当的有机金属物质如二乙烯基锌或二甲基（2-苯基乙炔基）铝处理，可以有效地实现中等大小的内酯衍生的硫代缩醛的亲核取代。有趣的是，立体化学的结果被发现在很大程度上取决于本地结构的基板。在某些情况下，在过渡态发展的左位空间相互作用被认为是负责观察到的非对映选择性。本发明的方法能够从容易获得的内酯前体有效地合成各种α，α′-取代的七至九元环醚。
Stereoselective synthesis of α,α′-substituted medium-sized cyclic ethers has been achieved by means of nucleophilic substitution of the corresponding lactone-derived thioacetals and their sulfone counterparts. Nucleophilic substitution of medium-sized lactone-derived thioacetals could be achieved efficiently either by (i) activation with NIS/TMSOTf in the presence of allyltrimethylsilane or TMSCN or by (ii) oxidation to the corresponding sulfones followed by treatment with an appropriate organometallic species such as divinylzinc or dimethyl(2-phenylethynyl)aluminum. Interestingly, the stereochemical consequence was found to be largely dependent on the local structure of substrates. In some cases, the gauche steric interaction developed in the transition state was considered to be responsible for the observed diastereoselectivity. The present method enables an efficient synthesis of a variety of α,α′-substituted seven- to nine-membered cyclic ethers from readily accessible lactone precursors.