Electroreductive Radical Cyclization of Ethyl 2-Bromo-3-allyloxy- and-3-(propargyloxy)propanoates Catalyzed by (Tetramethylcyclam)nickel(I) Electrogenerated at Carbon Cathodes in Dimethylformamide
作者:Ana P. Esteves、Danielle M. Goken、Lee J. Klein、Luis F. M. Leite、Maria J. Medeiros、Dennis G. Peters
DOI:10.1002/ejoc.200500478
日期:2005.11
Reductive intramolecular cyclization of ethyl 2-bromo-3-(3′,4′-methylenedioxyphenyl)-3-(propargyloxy)propanoate(1) and ethyl 3-allyloxy-2-bromo-3-(3′,4′-dimethoxyphenyl)propanoate (2) 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 salts, has been investigated. Cyclic
2-溴-3-(3',4'-亚甲二氧基苯基)-3-(炔丙氧基)丙酸乙酯(1)和3-烯丙氧基-2-溴-3-(3',4'-二甲氧基苯基)乙酯的还原分子内环化)丙酸酯 (2) 由(1,4,8,11-四甲基-1,4,8,11-四氮杂环十四烷)镍(I)、[Ni(tmc)]+ 促进,在含有二甲基甲酰胺的玻璃碳阴极上电生成已经研究了四烷基铵盐。在 1 和 2 存在下还原 [Ni(tmc)]2+ 的循环伏安图显示,[Ni(tmc)]+ 催化还原这两种化合物,其电位比直接还原溴酯所需的电位要高得多。在 1 和 2 存在下对 [Ni(tmc)]2+ 溶液进行控制电位电解期间,每个底物的催化还原通过碳-溴键的单电子裂解进行,形成自由基中间体,该中间体经过环化分别得到 2-(3',4'-亚甲二氧基苯基)-4-亚甲基四氢呋喃-3-羧酸乙酯(3) 和 2-(3',4'-二甲氧基苯基)-4-甲基四氢呋喃-3-羧酸乙酯 (