Japanese chemists report a simple method to add aryl-metal species to alkynoates, using a copper acetate catalyst.

Yoshihiko Yamamoto and colleagues from the Tokyo Institute of Technology established that the presence of catalytic amounts of copper acetate allows the conjugate addition of readily available arylboronic acids to alkynoates. This allows the reaction to work at ambient temperature, with precise stereoselectivity and good yields. 

Cuprate reagents were typically utilised for this reaction, however they required dry, low reaction temperatures and the stoichiometric use of metal salts - not ideal for the environment. It has been shown that the reactions could be catalysed instead by rhodium or palladium compounds, using bench-top reagents, however the demand for the platinum group metals increases year by year and the global deposits of these metals are limited. 

Yamomoto and colleagues therefore decided to pursue the use of an inexpensive non-precious metal catalyst, which still had the benefits that the precious metals provided. They successfully accomplished this goal, and can now obtain valuable cinnamate derivatives easily, cheaply and with less effect on the environment. In the future they plan to extend the simple Cu-catalyst system to other catalytic carbon-carbon bond formations. Yamomoto stated that "even asymmetric carbon-carbon bond formation reactions might be realised by the judicious combination of chiral non-racemic acids and appropriate copper salts." 

Rachel Davies