857502-05-7Relevant articles and documents
Silica-Supported Phosphine–Gold Complexes as an Efficient Catalytic System for a Dearomative Spirocyclization
Bibal, Brigitte,Buffière, Sonia,Cao, Zhen,Nlate, Sylvain,Oda, Reiko,Pouget, Emilie,Scalabre, Antoine
supporting information, p. 427 - 433 (2020/12/03)
The combination of metal catalyst and inorganic silica frameworks provides a greener approach to recyclable catalysis. In this study, three phosphine–gold chloride complexes have been successfully covalently grafted onto chiral silica nanohelices. The resulting 3D ensembles showed chiroptical properties that allowed the monitoring of the supported ligands. The heterogeneous gold chloride catalysts in cooperation with silver triflate exhibited high reactivity in various reactions, especially in the spirocyclization of aryl alkynoate esters, for which a catalytic loading of 0.05 mol % could be employed. The heterogeneous catalysts could be easily recovered and recycled seven or eight times without any loss of efficiency. By adding more silver triflate, 25 cycles with full conversion were achieved owing to a complex catalytic system based on silica and metallic species.
RADICAL TRAP IN FLUORIDATION OF IODONIUM SALT
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Page/Page column 19, (2008/06/13)
Decomposition of iodonium salts by a free radical process has been identified as a significant factor in the observed yield variability of fluoridation reactions using said iodonium salts. Accordingly, the inclusion of a free radical trap in the reaction mixture blocks the radical chain decomposition pathway for iodonium salts such that only the reaction leading to fluoridation can occur and the yield of aryl fluoride becomes high and reproducible. The reaction may also be carried out on solid phase. In both the solution and the solid phase the preferred method of the present invention is radiofluoridation.
