Expanding the chemical space of sp3-enriched 4,5-disubstituted oxazoles via synthesis of novel building blocks
作者:Evgeniy Y. Slobodyanyuk、Andrii A. Andriienko、Bohdan V. Vashchenko、Dmitriy M. Volochnyuk、Sergey V. Ryabukhin、Oleksandr O. Grygorenko
DOI:10.1007/s10593-019-02475-9
日期:2019.5
An efficient approach to the preparation of novel sp3-enriched 4,5-disubstituted oxazoles bearing a functional group at the C-4 position is described. The method commenced with synthesis of ethyl oxazole-4-carboxylates (13 examples, 63–99% yield), with subsequent function insertion to the heterocyclic core by late-stage functional group transformation. The LiBH4-mediated reduction of ethyl oxazole-4-carboxylates
描述了一种制备新颖的富含sp 3的4,5-二取代的恶唑的有效方法,该新的sp 3在C-4位置带有一个官能团。该方法开始于恶唑-4-羧酸乙酯的合成(13例,产率63-99%),随后通过后期官能团转化将功能插入杂环核心。由LiBH4介导的还原恶唑-4-羧酸乙酯的方法是唯一可以在数克范围内(最大40 g)优化的方法,其范围已通过制备13种具有(环)烷基,氟代烷基或N的醇来证明。-Boc-氨基烷基部分位于C-5位(产率47-89%)。通过制备氯化物(13例,产率为90-99%),叠氮化物(13例,产率为83-99%),胺(13例,产率为80-98%)和磺酰基证明了这些关键中间体的效用。氯化物(4个例子,产率68-97%)–用于合成和药物化学的高级构建基块。