Solvent and leaving group effects on the mono- vs. Dialkylation of alkali salts of diethyl malonate with 1,2-bis-, 1,2,4,5-tetrakis- and 1,2,3,4,5,6-hexakis-(Halomethyl)benzenes. A new insight into selectivity control of malonester synthesis
protic (“acidic”) solvents favor monoalkylation whereas aprotic (“inert”) solvents support dialkylation of diethyl malonate carbanion, exactly opposite results have been obtained in the reaction of the dibromide 7, tetrabromide 4 and hexabromide 1 in ethanol and dimethyl sulfoxide, the former solvent preferring strongly dialkylation (cyclization) and the latter monoalkylation. Investigation in a broader