Reactivity of Cyclic (Alkyl)(amino)carbenes (CAACs) and Bis(amino)cyclopropenylidenes (BACs) with Heteroallenes: Comparisons with their<i>N</i>-Heterocyclic Carbene (NHCs) Counterparts
作者:Glenn Kuchenbeiser、Michele Soleilhavoup、Bruno Donnadieu、Guy Bertrand
DOI:10.1002/asia.200900338
日期:2009.11.2
Similarly to NHCs, CAACa and BACa react with CO2 to give the corresponding betaines. Based on the carbonyl stretching frequencies of cis‐[RhCl(CO)2(L)] complexes, the order of electron donor ability was predicted to be CAACa≈BACa>NHCs. When the betaines νasym(CO2) values are used, the apparent ordering is BACa>NHCs≈CAACa that indicates a limitation for the use of IR spectroscopy in the ranking of ligand
与NHC类似,CAAC a和BAC a与CO 2反应生成相应的甜菜碱。根据顺式-[RhCl(CO) 2 (L)]配合物的羰基伸缩频率,预测电子供体能力的顺序为CAAC a ≈BAC a >NHCs。当使用甜菜碱 ν asym (CO 2 ) 值时,表观排序为 BAC a >NHCs≈CAAC a,这表明在配体 σ 供体能力排名中使用红外光谱的限制。尽管所有卡宾都与二硫化碳反应生成相应的甜菜碱,但第二当量的 CS2与BAC-CS2 反应生成双环噻吩并[2,3-二氨基]-1,3-二硫醇-2-硫酮,其中来自新颖的环膨胀过程的结果。令人惊讶的是,与NHC相比,CAAC a不与碳二亚胺反应,而BAC a专门产生扩环产物,类似于用CS 2获得的产物。使用 BAC b的四氟硼酸锂加合物作为卡宾替代物,可以捕获中间体脒盐。