Methylethers from Alcohols and Dimethyl Carbonate

Different synthetic approaches to methylethers by reaction of alcohols with dimethyl carbonate (DMC) used as reagent and solvent are herein reported. Direct methylation has been achieved in good yields using basic alumina or hydrotalcite KW2000 as catalyst both in batch and continuous-flow (C.-F.) conditions. A two-step synthetic approach, consisting of carboxymethylation of the parent alcohol followed by decarboxylation, has been also reported. Finally, the high-yielding methylation of the secondary hydroxyls groups of cyclic sugar isosorbide at reflux temperature (90 ∘C) by reaction with DMC is herein discussed. It is noteworthy that, despite methylation of secondary alcohols is quite complicated owing to the formation of elimination products, in this case study, dimethyl isosorbide was the sole product formed at low temperature and in quantitative yield.