To a mixture of the acid 14 (3.80 g, 13.3 mmol) and oxalyl chloride (5.8 mL, 66 mmol) in methylene chloride (60 mL) was added ca. 0.05 mL of N,N-dimethylformamide as a catalyst. After stirring 1 hr at ambient temperature, the reaction was evaporated in vacuo, diluted with methylene chloride, and reacted with benzyl alcohol (1.38 mL, 13.3 mmol) and 4-(N,N-dimethylamino)pyridine (1.60 g, 13.3 mmol). After stirring 16 hrs at ambient temperature, the solution was washed with dilute aqueous HCl, dilute aqueous NaHCO3, and brine, dried over Na2SO4, and filtered. The filtrate was then evaporated in vacuo giving a quantitative yield of gold oil. 1H NMR (300 MHz, CDCl3) δ 7.64 (t, 1H, J=1.5 Hz), 7.45-7.28 (m, 6H), 7.02 (m, 1H), 5.35 (s, 2H), 0.98 (s, 9H), 0.22 (s, 6H).
