Highly stereoselective Friedel-Crafts alkylations of unactivated benzenes by episulfonium ion cyclizations
Highly stereoselective Friedel-Crafts alkylations of unactivated benzenes by episulfonium ion cyclizations
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DOI：
10.1016/s0040-4039(01)02173-6
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发表时间：
2002-01-14
影响因子：
1.8
通讯作者：
Blanchette, HS
中科院分区：
文献类型：
--
作者：
Branchaud, BP;Blanchette, HS
高度对映体富集的异磺酸离子在活化苯环上的分子间加成可以实现手性弗里德尔-克拉夫特烷基化。未活化的苯要么不反应，要么具有较低的立体选择性。分子内环化反应应该比分子间加成反应快，因此，环化反应应该能够避免不希望发生的外消旋反应。本文报道的工作验证了这一假设，并证明了对映体富集的表磺离子在非活化苯环上的环化具有高度的立体选择性。(C) 2002 Elsevier Science Ltd.版权所有。
Intermolecular additions of highly enantiomerically enriched episulfonium ions onto activated benzene rings are known to accomplish chiral Friedel-Crafts alkylations. Unactivated benzenes are either unreactive or can give low stereoselectivities. Intramolecular cyclizations should be faster than intermolecular additions thus, cyclization reactions should be able to avoid undesired episulfonium ion racemization. The work reported here tests that hypothesis and demonstrates that cyclizations of enantiomerically enriched episulfonium ions onto unactivated benzene rings are highly stereoselective. (C) 2002 Elsevier Science Ltd. All rights reserved.