The use of dialkyl carbonates for safe and highly selective alkylations of methylene-active compounds. A process without waste production

摘要

The non-toxic compound dimethyl carbonate (DMC) can be used as a methylating and a udmethoxycarbonylating agent in place of methyl chloride and phosgene, respectively. We report here that udDMC and other dialkyl carbonates (DAlkCs: dimethyl, diethyl and dibenzyl carbonates) allow very udselective alkylations of a variety of CH ,-acidic compounds. Both arylacetonitriles and alkyl arylacetates udreact with DAlkCs to yield the mono-C-alkylated derivatives ( a-alkyl-a-arylacetonitriles and alkyl uda-alkyl-a-arylacetates) with a selectivity of up to 99%, at complete conversion. Likewise, the mono-C- udmethylation by DMC proceeds selectively also on (ary1oxy)acetonitriles and methyl (ary1oxy)acetates. udThe reactions are carried out at temperature of 180-220°C in the presence of weak bases (usually udK,CO,); under such conditions, DAlkCs efficiently replace the common and very toxic alkylating agents ud(dialkyl sulfates and alkyl halides). In addition to the high selectivity obtained and the intrinsic safety of udthe dialkyl carbonates, the reported reactions give rise to neither organic nor inorganic waste products.