Exploiting the 蟺-Acceptor Properties of Carbene-Stabilized Phosphorus Centered Trications [L3P] 3+: Applications in Pt(II) Catalysis
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- 作者：Javier Carreras ; Mahendra Patil ; Walter Thiel ; Manuel Alcarazo
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：October 10, 2012
- 年：2012
- 卷：134
- 期：40
- 页码：16753-16758
- 全文大小：433K
- 年卷期：v.134,no.40(October 10, 2012)
- ISSN：1520-5126
文摘
Reaction of tris(dimethylaminocyclopropenium) substituted phosphine 1 with K2PtCl4 afforded the bench stable complex 3 which upon treatment with Ag[CB11H6Cl6] turned out to be an excellent catalyst for the transformation of a variety of ortho-biaryl substituted alkynes into polycyclic homo- and heteroarenes of different size, shape, and curvature through a 6-endo-dig cyclization. This constitutes the first example ever reported of using a P1-centered trication as ligand in catalysis. The strong 蟺-acceptor character of 1 that derives from its three positive charges substantially increases the intrinsic 蟺-acidity of Pt in complex 1路PtCl2 and dramatically enhances its ability to activate 蟺-systems toward nucleophilic attack. As a consequence, a remarkable acceleration of the model transformation is observed when compared with other classical 蟺-acceptor ligands such as P(OPh)3 or P(C6F5)3. Moreover, the employment of 1 as ligand also expands the scope of this reaction to previously inaccessible substitution patterns. Kinetic studies and deuterium labeling experiments as well as density functional theory (DFT) calculations were performed in order to explain these findings.