Case study of a γ-butyrolactone alkylation with 1,3-dimethyl-2-imidazolidinone as a promoter

1,3-Dimethyl 2-imidazolidinone (DMI) is of lower toxicological risk than 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), hexamethyl-phosphorus triamide (HMPT), and hexamethylphosphoramide (HMPA). Formation of dialkylation byproducts is a common problem in lactone alkylation. DMI, used in stoichiometric amount, increases the rate of alkylation of gamma -butyrolactone 1 by >30-fold, therefore minimizing the dialkylation in multi-kilogram preparations. The isolated yield of the monoalkylated product 2 is >90%. The reaction protocol is also demonstrated to work on other lactone substrates and alkylating agents.