Development of a Practical and Efficient Synthesis of Chloromethyl 2-Ethoxy-2-methylpropanoate

An efficient synthesis of chloromethyl 2-ethoxy-2-methylpropanoate from 2-bromoisobutyric acid is reported. Four developments were key to this route: (i) a mild, base-mediated ethanolysis of a tertiary alkyl bromide, (ii) a sodium bisulfite purge of 2-methylacrylic acid, (iii) preparation of a thiomethyl ester via a formal Pummerer process with DMSO, and (iv) improved conversion of a thiomethyl ester to a chloromethyl ester through suppression of a competing chlorination pathway.