For almost two decades bulkier Pd-NHC catalysts, in particular those chlorinated on the NHC backbone, led to vastly improved reactivity in a wide cross-section of cross-coupling applications. In the case of alkyl-alkyl Negishi coupling, that this trend was found to be strikingly reversed. Moreover, bulkier catalysts always led to reduced BHE of secondary organozincs with aryl oxidative addition partners
近二十年来,体积更大的 Pd-NHC 催化剂,特别是那些在 NHC 主链上
氯化的催化剂,在广泛的交叉偶联应用中导致反应性大大提高。在烷基-烷基根岸偶联的情况下,发现这种趋势明显逆转。此外,体积更大的催化剂总是会导致具有芳基氧化加成伙伴的二级
有机锌的 BHE 降低——这是另一个相反的趋势。