Nucleophilic reactions of fluoroolefins. II. Regioselectivity and elimination-addition competition in the reaction of 1-phenylpentafluoropropenes with sodium ethoxide
作者:Wojciech Dmowski
DOI:10.1016/s0022-1139(00)81242-7
日期:1982.10
1-Phenylpentafluoropropene and its para-substituted analogs are susceptible to nucleophilic attack at both vinylic carbon atoms C-1 and C-2. They react with ethanolio sodium ethoxide to give predominantly substitution products, 1-ethoxy-1-phenyltetrafluoropropenes and 2-ethoxy-1-phenyltetrafluoropropenes , with only little formation of adducts, . 2-ethoxy-1H-1-phenylpentafluoropropanes . Alkenes ,
1-苯基五氟丙烯及其对位取代的类似物在乙烯基碳原子C-1和C-2上都容易受到亲核攻击。它们与乙醇钠乙醇溶液反应,主要生成取代产物1-乙氧基-1-苯基四氟丙烯和2-乙氧基-1-苯基四氟丙烯,而几乎没有加成物形成。2-乙氧基-1H-1-苯基五氟丙烷。烯烃,其中对位取代基X H,Cl和CF 3额外生成1,2-二乙氧基-1-苯基三氟丙烯,其中X = CF 3时还生成2,2-二乙氧基-1H-1-苯基四氟丙烷。乙醇离子对烯烃的亲核攻击的整体区域选择性表现出与取代基X的p值相关的Hammett型相关性:CH 3 O和CH 3基团倾向于攻击乙烯基碳C-1,而CF 3和Cl取代基则直接攻击烯烃的C-2碳。的1-乙氧基和1,2-二乙氧基取代的烯烃的E和Z异构体和形成于相当量,而2-乙氧基取代烯烃的E异构体总是与93形成- 97%的选择性。