Dirhodium(II) tetrakis(perfluoroalkylbenzoates) as partially recyclable catalysts for carbene transfer reactions with diazoacetates
作者:Andreas Endres、Gerhard Maas
DOI:10.1016/s0040-4020(02)00249-1
日期:2002.5
preference for the fluorous solvent. For the cyclopropanation reactions, the recovered catalyst was used in four subsequent reaction/workup cycles without significant loss of activity. In contrast, the catalyst could not be recovered from the carbenoid C–H insertion reaction with hexane; apparently, some by-products of this sluggish reaction, such as carbene dimers and oligomers, caused the deactivation
摘要 三高氟化二铑(II)四(苯甲酸盐),[Rh2(O2CRF)4,RF=C6H4-4-C6F13 ( 3 ) 和C6H3-3,5-di(CnF2n+1) (n=6:4 ; n = 8: 5 )],已经制备和表征。只有 4 和 5 适合用于氟合成,因为它们在氟溶剂中具有出色的溶解性。发现它们在含氟溶剂 1,1,2-三氯-1,2,2-三氟乙烷和全氟(甲基环己烷)中催化重氮化合物的以下类卡宾反应:使用重氮乙酸甲酯环丙烷化苯乙烯,分子间卡宾 C-H 插入与重氮乙酸甲酯形成己烷,并在分子内芳香族 C-H 插入 α-重氮-β-酮酯。除了第二种反应类型,由于催化剂偏爱含氟溶剂,因此可以通过液-液萃取(含氟溶剂-二氯甲烷)在很大程度上回收催化剂。对于环丙烷化反应,回收的催化剂用于四个随后的反应/后处理循环而没有明显的活性损失。相比之下,催化剂不能从与己烷的类碳烯 C-H 插入反应中回收;显然,这种缓慢反