To methyl hydroxypivalate (1.31 g, 9.89 mmol) were added tetrahydrofuran (40 ml), hydroxyphthalimide (3.23 g, 19.78 mmol) and triphenylphosphine (6.48 g, 24.73 mmol). After this solution was cooled to 0° C., diisopropyl azodicarboxylate (4.87 ml, 24.73 mmol) was added dropwise to the solution. While being allowed to warm gradually, the reaction mixture was stirred for 12 hours, and concentrated under reduced pressure. The residue was roughly purified by silica gel column chromatography to give the title compound (922 mg).
