A new catalytic procedure for atom-transfer radical addition (ATRA) and cyclization (ATRC) reactions is described. The combination of the ruthenium(III) complex [RuCl(2)Cp*(PPh3)] (Cp*: pentamethylcyclopentadienyl) with magnesium allows these reactions to be performed under mild conditions with high efficiency. In most cases, the catalyst concentrations required are significantly lower than those used
Highly Efficient Heterogeneous Aqueous Kharasch Reaction with an Amphiphilic Resin-Supported Ruthenium Catalyst
作者:Yohei Oe、Yasuhiro Uozumi
DOI:10.1002/adsc.200800359
日期:2008.8.4
An amphiphilic polystyrene-polyethylene glycol (PS-PEG) resin-supportedruthenium complex was designed and prepared. The polymeric Ru complex was found to promote the transition metal-catalyzed atom transfer radical addition of halogenated compounds to olefins, the Kharaschreaction, in water under heterogeneous as well as AIBN-free conditions with a high level of atom economy to meet green chemical
cycle: the radical addition reaction rate obeyed first-order kinetics that were dependent on the concentrations of the catalyst, styrene, and CCl4, while a saturation effect was observed at a high CCl4 concentration. In the presence of excess amounts of styrene, styrene coordinated in an η2-olefinic manner to the niobium center to decrease the reaction rate. No observation of oligomers or polymers of styrene