1752-02-9Relevant academic research and scientific papers
Polycationic ligands in gold catalysis: Synthesis and applications of extremely π-acidic catalysts
Carreras, Javier,Gopakumar, Gopinadhanpillai,Gu, Liangu,Gimeno, Ana,Linowski, Pawel,Petu?kova, Jekaterina,Thiel, Walter,Alcarazo, Manuel
supporting information, p. 18815 - 18823 (2014/01/06)
Very often ligands are anionic or neutral species. Cationic ones are rare, and, when used, the positively charged groups are normally appended to the periphery of the ligand. Here, we describe a dicationic phosphine with no spacer between the phosphorus atom and the two positively charged groups. This structural feature makes its donor ability poorer than that of phosphites and only comparable to extremely toxic or pyrophoric compounds such as PF 3 or P(CF3)3. By exploiting these properties, a new Au catalyst has been developed displaying a dramatically enhanced capacity to activate π-systems. This has been used to synthesize very sterically hindered and naturally occurring 4,5-disubstituted phenanthrenes. The present approach is expected to be applicable to the development and improvement of many other transition metal catalyzed transformations that benefit from extremely strong π-acceptor ligands. The mechanism of selected catalytic transformations has been explored by density functional calculations.
On the Synthesis of a Phenanthrene-2,7-quinone
Hewgill, Frank R.,Slamet, Riskiono,Stewart, Jeffery M.
, p. 3033 - 3042 (2007/10/02)
Oxidative coupling of 2,2',4,4'-tetramethoxystilbene-3,3'-diol 51 gave a 51percent yield of 1,3,6,8-tetramethoxyphenanthrene-2,7-quinone 52, the first isolated example of a quinone of this type.Similar oxidation of the corresponding diphenylethane 55 gave
