Acylated 2,2-dimethylaziridines: regioselectivity of ring opening by sodium thiophenolate; borderline SN2 due to planarization of nitrogen pyramid

Pen yuan Lin, Konstantinos Bellos, Helmut Stamm, Andreas Onistschenko

研究成果: 雜誌貢獻文章同行評審

38 引文 斯高帕斯(Scopus)

摘要

2,2-Dimethylaziridines 1 carrying a COR group on nitrogen are opened by PhS⊖ with a regioselectivity RS = abnormal:normal ≥ 20 in MeOH and 5-16 in THF. Practically no influence of COR on RS was found except for the poorest oxidant 1g (R = tBu) that gave the highest RS (95, MeOH). This rules out an SET mechanism for the abnormal opening. Absence of homolytic ring opening is directly shown by the failure to detect products resulting from cyclization of a homolytically formed radical when COR is cinnamoyl (1f). Direct nucleophilic attack is indicated by suppression of any reaction with PhS⊖ when the steric hindrance is increased (N-benzoylaziridine 13). The observed SN2 borderline behaviour with 1 is explained by reaction in a flattened nitrogen conformation of the otherwise poorly reactive 1. Carboxamide resonance in this (nearly) planar conformation generates a substantial positive charge on N which will shift the mechanism closer to SN1 by partial heterolysis of the N-CMe2 bond prior to attack by PhS⊖.

原文英語
頁(從 - 到)2359-2372
頁數14
期刊Tetrahedron
48
發行號12
DOIs
出版狀態已發佈 - 三月 20 1992
對外發佈Yes

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

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