Selective Mono-methylation of Arylacetonitriles and Methyl Arylacetates by Dimethyl Carbonate

Both arylacetonitriles and methyl arylacetates react with dimethyl carbonate (DMC) (20 molar excess) at 180-200 "C in the presence of K,CO, to produce monomethylated 2-arylpropionitriles and methyl 2-arylpropionates, respectively, with a selectivity > 99.5%. The reaction, with wide application, proceeds by DMC acting as a methoxycarbonylating agent towards the ArCH -X anion (X = CN, C0,Me) and as a methylating agent to Arc-(C0,Me)X. DMC also proved to be the best solvent for such reactions