Regioselective Synthesis of α-Methyl 2-Methyleneglutarate via a Novel Lactonization−Elimination Rearrangement

A facile route to the α-methyl ester of 2-methyleneglutarate via a three-step sequence from 3-hydroxymethylcyclopentene is described. Regioselective formation of the monoacid from a diester precursor proceeds via a novel fluoride-mediated, tandem deprotection/rearrangement of O-silyl 2-(hydroxymethyl)dimethylglutarate.