Dithiocarbamate as a Carbonyl Alternative in Pd-Catalyzed Carbonylative Homocoupling of Organoboronic Acids

We have developed a novel protocol for carbonylative
homocoupling
of arylboronic acids using dithiocarbamate esters as the carbonyl
alternative. A series of arylboronic acids underwent smooth reaction
with dithiocarbamate ester (Me2NCS2Me) in the
presence of Pd(PPh3)2Cl2 catalyst,
Cu(OAc)2·H2O additive, and Na2CO3 in DCE solvent, producing the biaryl ketones efficiently.
The mechanism has been studied with the help of several control experiments
that reveal the probability of thioamide intermediacy. Chemoselective
homocoupling allows the postsynthetic modification of the product.