Enantioselective Construction of Chiral Cyclopropa[c]coumarins via Lewis Base-Catalyzed Cyclopropanation
Enantioselective Construction of Chiral Cyclopropa[c]coumarins via Lewis Base-Catalyzed Cyclopropanation
复制标题
路易斯碱催化环丙烷化反应对映选择性构建手性环丙[c]香豆素
DOI：
10.1021/acs.joc.0c01782
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发表时间：
2020-12-04
影响因子：
3.6
通讯作者：
Zeng, Xing-Ping
中科院分区：
文献类型：
--
作者：
Sun, Jun-Chao;Wang, Xiao-Hui;Zeng, Xing-Ping
首次报道了手性环丙烯并[c]香豆素的高对映选择性合成。以市售的（双）金鸡纳生物碱（DHQ）（2）PYR为手性刘易斯碱催化剂，Cs_2CO_3为非手性碱，香豆素-3-羧酸酯和3-苯甲酰基香豆素与2-溴乙酸叔丁酯反应，得到相应的具有3个连续手性立体中心的环丙并[c]香豆素，其ee值分别为83- 93%ee和90- 97%ee。该反应建议通过原位生成的铵叶立德中间体进行。
The first highly enantioselective construction of chiral cyclopropa[c]coumarins was described. Using commercially available (bis)cinchona alkaloid (DHQ)(2)PYR as the chiral Lewis base catalyst, together with Cs2CO3 as the achiral base, the reaction of a series of coumarin-3-carboxylate and 3-benzoyl coumarins with tert-butyl 2-bromoacetate could give rise to the corresponding cyclopropa[c]coumarins bearing three continuous chiral stereocenters in 83-93% ee and 90-97% ee, respectively. The reaction is proposed to proceed via an in situ generated ammonium ylide intermediate.