Electroreductive Intramolecular Cyclization of a Bromo Propargyloxy Ester Catalyzed by Nickel(I) Tetramethylcyclam Electrogenerated at Carbon Cathodes in Dimethylformamide
作者:Ana P. Esteves、Danielle M. Goken、Lee J. Klein、Maria A. Lemos、Maria J. Medeiros、Dennis G. Peters
DOI:10.1021/jo026102k
日期:2003.2.1
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate and characterize the reductive intramolecular cyclization of ethyl 2-bromo-3-(3',4'-dimethoxyphenyl)-3-(propargyloxy)propanoate (1) promoted by (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)nickel(I), [Ni(tmc)](+), electrogenerated at glassy carbon cathodes in dimethylformamide containing tetraalkylammonium
循环伏安法和控制电位电解已用于研究和表征由(1, 4,8,11-四甲基-1,4,8,11-四氮杂环十四烷)镍(I)[Ni(tmc)](+)在含四烷基铵盐的二甲基甲酰胺中的玻璃碳阴极上电生成。在1存在下还原[Ni(tmc)](2+)的循环伏安图显示,[Ni(tmc)](+)催化还原1的电势比直接还原1所需的电势更正。含[Ni(tmc)](2+)和1的溶液的电位电解 后者的催化还原通过碳-溴键的单电子裂解形成自由基中间体而进行环化后得到2-(3',4'-二甲氧基苯基)-3-(乙氧基羰基)-4-亚甲基四氢呋喃(2 )。在碱的存在下(无论是电生成的还是有意添加为叔丁醇钾),2均会重排以生成2-(3',4'-二甲氧基苯基)-3-(乙氧基羰基)-4-甲基-2,5-二氢呋喃(3)。提出了一种机械方案来解释通过循环伏安法和控制电位电解所获得的结果。-二甲氧基苯基)-3-(乙氧基羰基)-4-甲基-2,5-二