Competitive and Selective Csp3Br versus Csp2Br Bond Activation in Palladium-Catalysed Suzuki Cross-Coupling: An Experimental and Theoretical Study of the Role of Phosphine Ligands
作者:Cristian Mollar、Maria Besora、Feliu Maseras、Gregorio Asensio、Mercedes Medio-Simón
DOI:10.1002/chem.201001113
日期:2010.12.3
hindered phosphine ligands such as P(o‐tol)3 and P(1‐naphthyl)3 reversed the selectivity, conducting the cross‐coupling at the Csp2‐Br. Identical trends were observed in external competition experiments carried out with bromomethyl sulfoxide and different substituted bromoarenes. DFT and DFT/MM calculations showed that the selectivity observed is mainly due to the different facility of the ligands to dissociate
在具有竞争性的分子内钯催化的具有两个不同杂交亲电碳的二溴亚砜1a的Suzuki-Miyaura竞争分子内,膦配体已被证明对反应性和选择性有影响。发现在不受阻碍的膦(例如PPh 3或黄磷)存在下,sp 3杂化碳上的溴键被选择性取代。使用受阻的膦配体,例如P(o- tol)3和P(1-萘基)3会逆转选择性,在Csp 2处进行交叉偶联‐Br 在使用溴甲基亚砜和不同取代的溴芳烃进行的外部竞争实验中,观察到了相同的趋势。DFT和DFT / MM计算表明,观察到的选择性主要是由于配体解离的便利性不同所致。双膦催化剂优选在sp 3碳上偶联,而单膦催化剂优选在sp 2碳上偶联。