Stereoselective Synthesis of Medium-Sized Cyclic Ethers: Application of <i>C</i>-Glycosylation Chemistry to Seven- to Nine-Membered Lactone-Derived Thioacetals and Their Sulfone Counterparts
作者:Yuto Suga、Haruhiko Fuwa、Makoto Sasaki
DOI:10.1021/jo4025545
日期:2014.2.21
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
已经通过相应的内酯衍生的硫缩醛及其砜对应物的亲核取代,实现了α,α'-取代的中型环状醚的立体选择性合成。中型内酯衍生的硫缩醛的亲核取代可以通过(i)在烯丙基三甲基硅烷或TMSCN存在下用NIS / TMSOTf活化,或(ii)氧化成相应的砜,然后用适当的有机金属物质处理来有效地实现作为二乙烯基锌或二甲基(2-苯基乙炔基)铝。有趣的是,发现立体化学结果在很大程度上取决于底物的局部结构。在某些情况下,在过渡状态下形成的gauche空间相互作用被认为是所观察到的非对映选择性的原因。