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To 10.0 g (41.3 mmol) of 4-benzyloxyphenylacetic acid (31) was added, 20 mL of acetic anhydride and 20 mL of pyridine, which was heated to reflux with stirring under argon atmosphere for 6 hours. Solvents were evaporated and residue dissolved in CHCl3 (50 mL) and washed with 1N NaOH (2×50 mL). Dried organic layer (MgSO4), filtered, and evaporated to 11.8 g of an amber oil. Vacuum distillation at 0.1 mm Hg in an oil-bath set to 170° C. followed by silica gel chromatography eluting with 8/2 CH2Cl2-hexanes gave 2.68 g (27%). 1H NMR (CDCl3) □δ□ 2.14 (s, 3H), 3.63 (s, 2H), 5.05 (s, 2H), 6.94 (d, 2H, J=8.7 Hz), 7.10 (d, 2H, J=8.7 Hz), 7.26-7.47 (m, 5H).

1. temperatureto reflux
2. customSolvents were evaporated
3. dissolutionresidue dissolved in CHCl3 (50 mL)
4. washwashed with 1N NaOH (2×50 mL)
5. filtrationDried organic layer (MgSO4), filtered
6. customevaporated to 11.8 g of an amber oil
7. distillationVacuum distillation at 0.1 mm Hg in an oil-bath
8. customset to 170° C.
9. washeluting with 8/2 CH2Cl2-hexanes
10. customgave 2.68 g (27%)