The reaction of excess TMSCl and LiCCl2Br at low temperature is a technically simple high yield route to TMSCCl2Br. The latter is a stable source of the dichlorobromomethide carbanion, which undergoes 1,4‐addition with cyclic nitroalkenes and (E)‐fumarates leading to dichlorocyclopropanes after bromide expulsion. For nitrostyrenes the reaction arrests at the 1,4‐addition product. Low temperature NMR
过量的TMSCl和LiCCl的反应2
溴在低温下是技术上简单的高产率路线TMSCCl 2
溴。后者是二
氯溴甲烷碳负离子的稳定来源,它与环硝基烯烃和(E)
富马酸酯进行1,4加成反应,在
溴化物排出后会生成二
氯环丙烷。对于硝基
苯乙烯,反应停滞在1,4加成产物上。低温NMR光谱研究和DFT计算表明形成了[ate]物种[(
硝酸盐)Si
FMe 3 ] -,当TMSF在10–20°C沸腾时,生成
环丙烷。DFT计算还支持
氟化物和
乙酸盐作为
促进剂之间的实验差异。