Pd Nanoparticle-Catalyzed Stereospecific Mizoroki-Heck Arylation of cis -1,2-Disilylarylethylenes.

In the presence of catalytic amounts of Pd nanoparticles, generated from Pd 2 dba 3 /Ag(I), cis -1,2-ditrimethylsilylarylethylenes undergo with aryl iodides a stereospecific Mizoroki-Heck arylation leading to trans -ditrimethylsilyldiarylethylenes. This chemoselectivity is in contrast to that of their trimethylgermyl analogues, which are arylated at the position of the C-Ge bonds. trans -1,2-Ditrimethylsilylarylethylenes are completely unreactive under the standard reaction conditions. The reaction tolerates the presence of boryl, silyl, or bromine substituents on the aryl iodides. From a mechanistic point of view, the process involves syn -arylpalladation followed by syn -dehydropalladation.