Metal-free tandem cyclization/hydrosilylation to construct tetrahydroquinoxalines,Green Chemistry

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Metal-free tandem cyclization/hydrosilylation to construct tetrahydroquinoxalines
Green Chemistry ( IF 9.3 ) Pub Date : 2017-11-03 00:00:00 , DOI: 10.1039/c7gc03095a
Yixiao Pan _{1,

2,

3,

4} , Changjun Chen _{1,

2,

3,

4} , Xin Xu _{1,

2,

3,

4} , Haoqiang Zhao _{1,

2,

3,

4} , Jiahong Han _{1,

2,

3,

4} , Huanrong Li _{1,

2,

3,

4} , Lijin Xu _{1,

2,

3,

4} , Qinghua Fan _{4,

5,

6,

7} , Jianliang Xiao _{1,

8,

9,

10}

Affiliation

A one-pot tandem procedure involving cyclization and sequential hydrosilylation of imines and amides under the catalysis of B(C₆F₅)₃ has been developed for the step-economical construction of 1,2,3,4-tetrahydroquinoxalines directly from readily available 1,2-diaminobenzenes, α-ketoesters and low-cost, safe polymethylhydrosiloxane (PMHS). This metal-free approach provides various products in good to excellent yields, and displays a wide range of substrate scope and a high degree of functional group tolerance even to reduction-sensitive moieties. The choice of hydrosilanes is critical to the catalysis, and PMHS has proved to be optimal. Decreasing the amount of PMHS could enable the reaction to stop at the 3,4-dihydroquinoxalin-2(1H)-one stage. The procedure is convenient and scalable, and neither a dried solvent nor an inert atmosphere is required. Moreover, the enantioselective construction of these products was explored, and promising results were achieved.

中文翻译：

无金属串联环化/氢化硅烷化以构建四氢喹喔啉

已经开发了一种单锅串联程序，涉及在B（C ₆ F ₅）₃催化下亚胺和酰胺的环化和顺序氢化硅烷化，可直接从容易获得的步骤经济地构建1,2,3,4-四氢喹喔啉。 1,2-二氨基苯，α-酮酸酯和低成本，安全的聚甲基氢硅氧烷（PMHS）。这种无金属的方法可提供各种产品，具有良好的优良收率，并显示出宽范围的底物范围和高度的官能团耐受性，甚至对还原敏感的部分也是如此。氢硅烷的选择对催化至关重要，事实证明PMHS是最佳选择。减少PMHS的量可使反应在3,4-dihydroquinoxalin-2（1 H）-一个阶段。该过程方便且可扩展，并且不需要干燥的溶剂或惰性气氛。此外，探索了这些产品的对映选择性结构，并获得了可喜的结果。

更新日期：2017-11-16

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