A solution of the bromomethyl compound 1 (3.13 g, 8.24 mmol) and tributylphosphine (5.00 g, 24.7 mmol) in Me2SO (200 mL) was kept 20 hours at 20°-23° C., then gradually warmed during 90 minutes to 55° C. for 30 minutes, and cooled to 20-23° C. Methyl 4-(propionyl)benzoate (1.58 g. 8.22 mmol) was then added, followed by sodium hydride (660 mg of 60% dispersion in oil, 16.5 mmol). Complete solution occurred readily. After 44 hours at 20°-23° C., the solution was heated at 70°-75° C. for 64 hours. Removal of the Me2SO by distillation in vacuo (less than 1 mm, bath to 55° C.) followed. The syrupy residue was stirred with Et2O until the yellow solid that formed was dispersed. The solid was collected with the aid of Et2O, air dried, then stirred thoroughly with H2O before it was again collected and dried in vacuo (78° C.) over NaOH pellets and P2O5) Crude 3 (2.31 g, 77% crude yield) was combined with a sample from another run and the combined batch was purified by flash chromatography on silica gel (230-400 mesh) using elution by CHCl3 -MeOH (9:1). Fractions found by TLC to be homogeneous (UV detection) were pooled and evaporated to give pure 3. The purified material amounted to 50% recovery of material applied to the column. Spectral data: mass, m/z 364, (MH+) for C20H21N5O2.
