尽管有许多试剂组合可以引发多烯环化,但尚未证明简单的亲电子卤素源作为此类过程的促进剂广泛有效。本文描述了一类易于制备且稳定的试剂,能够对源自香叶醇、法呢醇和橙花醇的各种富电子和缺电子萜烯进行此类转化,从而能够有效合成多种复杂的氯- 、含溴和含碘的多环骨架。迄今为止的努力已导致抗 HIV 天然产物 Peyssonol A 的第一个外消旋实验室全合成和结构修订,以及 peyssonoic acid A 的有效和简洁的首次全合成。他们还允许正式的外消旋全合成 aplysin- 20、萝莉莉德、K-76、和 Stemodin 将通过通常比以前的努力更短、产量更高且更具环保意识的途径来实现。还描述了使用该试剂类的手性形式进行对映选择性烯烃卤化的初步尝试。
NXS, Morpholine, and HFIP: The Ideal Combination for Biomimetic Haliranium-Induced Polyene Cyclizations
作者:Andreas M. Arnold、Alexander Pöthig、Markus Drees、Tanja Gulder
DOI:10.1021/jacs.8b00113
日期:2018.3.28
contrast to Nature that accomplishes polyenecyclizations seemingly with ease, such transformations are difficult to conduct in the lab. In our program dealing with the development of selective halogenations of alkenes, we now asserted that standard X+ reagents are perfectly suited for the biomimetic cation-π cyclization of both electron rich and poor linear polyenes in the presence of the Lewis base