Preparation of New Buchwald-Type Secondary Phosphine Oxide Ligands and Applications in Suzuki−Miyaura Reactions
作者:Dan-Fu Hu、Chia-Ming Weng、Fung-E Hong
DOI:10.1021/om101132t
日期:2011.3.14
Two air- and moisture-stable secondary phosphine oxides (SPOs), namely, 2-(tert-butylhydrophosphoryl)-1-(2-R-phenyl)-1H-imidazole (3a, R = H; 3b, R = OMe) were prepared and characterized. A tautomeric equilibrium exists between the secondary phosphine oxide 3a (or 3b) and its corresponding phosphinous acid 3a′ (or 3b′). The reaction of phosphinous acid 3a′ (or 3b′) with Pd(COD)Cl2 (or PdBr2) yielded
两种对空气和水分稳定的仲氧化膦(SPO),即2-(叔丁基氢磷酰基)-1-(2-R-苯基)-1 H-咪唑(3a,R = H; 3b,R = OMe )已准备好并进行了特征化。在仲氧化膦3a(或3b)与其对应的次膦酸3a'(或3b')之间存在互变异构平衡。次膦酸3a'(或3b')与Pd(COD)Cl 2(或PdBr 2)反应生成相应的单钯配合物双(2-(叔丁基氢磷酰基)-1-(2-R-苯基)-1 H咪唑)PDX 2(图5a,R = H,X =氯;图5b,R = OME,X =溴)在顺式-形式以及二钯配合物[(μ 2 -2-(叔-butylhydrophosphoryl)-1- (2-R-苯基)-1 H-咪唑-N,P)Pd(I)X] 2(6a,R = H,X = Cl;6b,R = OMe,X = Br)。次膦酸3a'和3b'在6a和6b的形成中充当P,N螯合配体,其特征在于直接的Pd(I)-P