Selective mono-methylation of arylacetonitriles and methyl arylacetates by dimethylcarbonate - A process without production of waste

The reaction of arylacetonitriles and methyl arylacetates with dimethylcarbonate (DMC) at 180-220 degrees C in the presence of a weak base (K2CO3), produces the mono-methylderivatives (2-arylpropionitriles and methyl 2-aryl propionates, respectively) with a selectivity higher than 99%. This reaction has a wide range of applications since the products obtained are well known intermediates for non-steroidal antiinflammatory drugs. Contrary to the usual methylating agents (methylchloride and dimethyl sulfate), the reaction with the non-toxic DMC takes place with only a catalytic amount of the base; accordingly, no inorganic salts are produced. The reaction proceeds both under continuous-flow and batchwise conditions. The mechanism is discussed