XL-Xantphos: Design and Synthesis of a Mechanistic Probe of Xantphos <i>O</i>-Coordination in Catalytic Reactions
作者:Gregory T. Whiteker、Fangzheng Li、Robert D. J. Froese、Michael L. Tulchinsky、Amaruka Hazari、Jerzy Klosin
DOI:10.1021/acs.organomet.9b00141
日期:2019.5.13
The synthesis and characterization of an analog of the Xantphos ligand that is geometrically incapable of coordination of the xanthene bridging oxygen atom is reported. This new ligand, XL-Xantphos, ((9,9-dimethyl-9H-xanthene-4,5-diyl)bis(4,1-phenylene))bis(diphenylphosphane), was studied in homogeneous, catalytic reactions for comparison with Xantphos. The XL-Xantphos ligand performed essentially
据报道,Xantphos配体的类似物的合成和表征在几何上不能与氧杂蒽酮桥接氧原子配位。这种新的配体XL-Xantphos(((9,9-dimethyl-9 H-Xanthene-4,5-diyl)bis(4,1-phenylene)bis(diphenylphosphane)在均相催化反应中进行了研究,以与Xantphos进行比较。XL-Xantphos配体在Rh催化的1-辛烯加氢甲酰化反应中与Xantphos基本相同,这表明对线性醛的高区域选择性是由于这些配体的大咬合角而不受氧与金属的配位影响。类似地,在Xantphos和XL-Xantphos之间,Pd催化的4-溴茴香醚与二甲基羟胺盐酸盐的酰胺羰基化反应没有差异。在理论上的DLPNO–CCSD(T)水平上对Pd(II)膦配合物的计算表明,这些配体对顺式和反式具有不同的偏好协调模式。XL-Xantphos配体对反式螯合结构具有热力学偏好,而顺式-[(Xantphos)PdCl