Dose Stevens Rearrangement Really Proceed via a [1,2] Radical Rearrangement?

史蒂文斯重排真的是通过[1,2]激进重排进行吗？

• 批准号: 05671764
• 负责人: SHIRAI Naohiro
• 金额: $ 1.09万
• 依托单位: Nagoya City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05671764/
• 关键词: AMMONIUM YLIDE; DESILYLATION; STEVENS REARRANGEMENT; SOMMELT-HAUSER REARRANGEMENT; SIGMATROPIC REARRANGEMENT; RADICAL REARRANGEMENT; [1,2] REARRANGEMENT; [2,3] REARRANGEMENT; アンモニウム・イリド; Sommelet-Hauser転位; アンモニウムイリド

Stevens rearrangement is a typical reaction of ammonium ylides. The mechanism has been the subject of much study, and a [1,2] radical rearrangement pathway in the solvent cage has been considered. In the papers that reported high yields of Stevens products, most of the migrating groups were benzyl groups.In my previous studies of chemical behavior of N,N-dimethylbenzylammonium alkylides, produced by fluoride ion induced desilylation of N-benzyl-N,N-dimethyl-alpha-(trimethylsilyl) alkylammonium halides, I reported that Stevens products were formed from isotoluenes which were formed by a [2,3] sigmatropic rearrangement of the alkylides (two steps mechanism). There is no [1,2] shift from the alkylides to the Stevens products.In this research project, I investigated the chemical behavior of N-alkyl-N,N-dimethylammonium benzylides. When a migrating group (R) was an alkyl, no rearrangement occurred but moderate yields of Stevens products were obtained when R was CH_2CN.In the two steps mechanism, is chirality of the migrating group retained? Stevens product prepared from optically-active S-(-)-N,N-dimethy-N-(trimethylsilyl) methyl-1-phenethylammonium iodide retained the chirality during a [2,3] rearrangement followed by a [1,3] shift.These results revealed that Stevens rearrangement has two reaction mechanisms.

史蒂文斯的重排是铵和铵的典型反应。该机制已成为大量研究的主题，并且已经考虑了溶剂笼中的[1,2]自由基重排途径。在报道史蒂文斯产品产量高产量的论文中，大多数迁移群是苄基群。在我先前关于N，N-二甲基苯基苯基烷基化的化学行为的研究中，氟离子诱导的N-苯甲酰基N，N-二酰基N-二甲基 - α-甲基二甲基硅烷基于N-二甲基 - 甲基硅烷基甲基烷基烷基烷基化的N-苯甲酰基-N的脱酰基化产生的烷基化烷基化烷基化烷基化的烷基化。由烷基化的[2,3] Sigmatropic重排（两个步骤机理）形成的异醇烯。没有[1,2]从烷基化的[1,2]转移到史蒂文斯产品。在这项研究项目中，我研究了N-烷基-N，N-二甲基铵的化学行为。当迁移组（r）是烷基时，没有重新排列，但是当r是ch_2cn时，史蒂文斯产物的收率中等。史蒂文斯（Stevens）产品由光学活性S - （ - ） - N，N-二甲基-N-（三甲基甲硅烷基）甲基-1-苯基胺碘化物碘化物保留在[2,3]重排期间的手性。