Rhodium-catalyzed silylation of aromatic carbon-hydrogen bonds in 2-arylpyridines with disilane.
The rhodium(I)-catalyzed regioselective silylation of the ortho carbon-hydrogen bond in 2-arylpyridines with disilane is described. For example, the reaction of 2-(2-methylphenyl)pyridine with 2 equivalents of hexamethyldisilane in the presence of 5 mol % [RhCl(cod)](2) (cod=1,5-cyclooctadiene) in o-xylene at 130 degrees C for 15 h gave 2-[2-methyl-6-(trimethylsilyl)phenyl]pyridine in 86 % yield. In contrast to silylation with hydrosilanes, hydrogen acceptors are not required to achieve high conversion. A variety of substituents, including alkoxy, amine, ester, and fluorinated groups, are compatible with this catalysis. When substrates containing two ortho C-H bonds are used, monosilylated products are obtained selectively by utilizing the 3-methyl-2-pyridyl group as a directing group.
Tobisu
Mamoru
M
Frontier Research Base for Young Researchers, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan. tobisu@chem.eng.osaka-u.ac.jp
Ano
Yusuke
Y
Chatani
Naoto
N