Metallation reactions. XXV. A re-examination of the metallation reaction of (alkylthio)fluorobenzenes
作者:M.G. Cabiddu、S. Cabiddu、E. Cadoni、C. Fattuoni、S. Melis
DOI:10.1016/s0022-1139(99)00097-4
日期:1999.9
The metallation of (alkylthio)fluorobenzenes by organolithium compounds, lithium amides and butyllithium/potassium tert-butoxide superbasic mixture was re-examined. To avoid the formation of defluorinated compounds all the reactions must be carried out below −80°C. The para-substituted 1a and 1b showed a regiochemistry directed by the halogen; the ortho-derivative 1c underwent metallation ortho to
重新检查了有机锂化合物,酰胺化锂和丁基锂/叔丁醇钾叔丁基超碱混合物对(烷硫基)氟苯的金属化作用。为了避免形成脱氟化合物,所有反应必须在-80℃以下进行。对位取代的1a和1b表现出由卤素指导的区域化学;当用四甲基哌啶锂处理邻位衍生物1c时,邻位金属与卤素发生邻位金属化反应,用丁基锂进行α-金属化反应,而仲丁基锂的选择性较低。化合物1a和1c允许制备双取代的产品。在高于-80°C的温度下,形成越来越多的脱卤产物,其形成可以通过芳烃的中间体来解释。