摘要/Abstract
报道了一种新型的Zn/Y双金属接力催化的串联反应，该方法通过Zn（OTf）2和Y（OTf）3接力催化，一锅法进行分子内环异构化/分子间阿尔德-烯反应构建α-羟基酰胺噁唑衍生物.产物的形成主要是由Zn（OTf）2活化炔丙基酰胺的叁键发生分子内的环化反应构建噁唑啉中间体，由Y（OTf）3催化1-苄基吲哚啉-2，3-二酮类化合物，继而由噁唑啉中间体与1-苄基吲哚啉-2，3-二酮类化合物发生分子间阿尔德-烯反应，实现了α-羟基酰胺噁唑衍生物的合成.优化部分的对比实验证实，Zn（OTf）2和Y（OTf）3的存在对于该串联反应都是必须条件.所有反应都是将各反应物和试剂一次性加入，在空气氛围下100℃加热进行反应.该方法反应条件简单、原子经济性高、官能团兼容性好，对噁唑衍生物合成具有重要的意义.
关键词: 接力催化, 环异构化, 阿尔德-烯反应, 噁唑衍生物
A novel tandem metal relay catalytic system of Zn/Y has been successfully developed. By using this unprecedented Zn(OTf)2/Y(OTf)3 bimetallic relay catalytic system, a variety of oxazole α-hydroxy amides derivatives were obtained from easily available N-(propargyl)-arylamides and various 1-benzylindoline-2,3-dione derivatives through intramolecular cycloisomerization/intermolecular Alder-ene reaction under mild conditions. The first step of the one-pot procedure is that Zn(OTf)2 acts as a π acid to activate the triple bond of N-(propargyl)-arylamides, and a subsequent intramolecular 5-exo-dig cyclization forms the oxazoline intermediate. Separately, Y(OTf)3 acts as Lewis acid, then oxazoline intermediate and 1-benzylindoline-2,3-dione derivatives are transformed to the oxazole α-hydroxy amide derivatives in good to excellent yields in an intermolecular Alder-ene reaction. Control experiments in the optimization section disclose the fact that Zn(OTf)2 and Y(OTf)3 are both indispensable for this intramolecular cycloisomerization/intermolecular Alder-ene reaction. Generally, the synthetic reactions run under air atmosphere by heating all the substrates and reagents in one-pot at 100℃. The present method benefits from the distinctive features of simple reaction conditions, high atom economy and broad substrate tolerance. It is of great significance for the synthesis of oxazole derivatives.
Key words: relay catalysis, cycloisomerization, Alder-Ene reaction, oxazole derivatives
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