A Co(II)-catalyzed asymmetric ring opening reaction of spiro-epoxyoxindoles with allylboron,Organic Chemistry Frontiers

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A Co(II)-catalyzed asymmetric ring opening reaction of spiro-epoxyoxindoles with allylboron
Organic Chemistry Frontiers ( IF 4.6 ) Pub Date : 2020/02/18 , DOI: 10.1039/d0qo00072h
Liang Wu _{1,

2,

3,

4,

5} , Qihang Shao _{1,

2,

3,

4,

5} , Li Kong _{3,

4,

5,

6} , Jianzhong Chen _{1,

2,

3,

4,

5} , Quhao Wei _{3,

4,

5,

6} , Wanbin Zhang _{1,

2,

3,

4,

5}

Affiliation

Stereoconvergent reactions of epoxides are challenging and very limited. Herein, we report the first stereoconvergent ring opening allylation of epoxides, which was catalysed by a Co(II)/bisoxazoline catalyst, to realize the reaction between spiroepoxyoxindoles and potassium allyltrifluoroborate. This catalytic system can tolerate a wide range of spiroepoxyoxindoles. The desired chiral oxindoles bearing quaternary stereocenters could be prepared with yields of 64–90% and enantioselectivities of 57–78%. A gram-scale reaction showed the practical applicability of this enantioselective catalysis. Furthermore, preliminary mechanistic studies indicate that this reaction proceeds via a sequential epoxide-ring-opening and enantioselective addition process.

中文翻译：

Co（II）催化螺-环氧肟基吲哚与烯丙基硼的不对称开环反应

环氧化物的立体收敛反应具有挑战性并且非常有限。本文中，我们报道了环氧化物的第一个立体收敛性开环烯丙基化，该环氧化物被Co（II）/双恶唑啉催化剂催化，以实现螺环氧基氧吲哚与烯丙基三氟硼酸钾之间的反应。该催化体系可耐受多种螺氧基环氧吲哚。可以制备所需的带有四级立体中心的手性羟吲哚，产率为64–90％，对映选择性为57–78％。克级反应表明该对映选择性催化的实际适用性。此外，初步的机理研究表明，该反应通过顺序的环氧化物开环和对映选择性加成过程进行。

更新日期：2020-03-19

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