No. 5217614, tert-butyl (E)-(2S,3S)-3-[(S)-2-(4-but-2-ynyloxy-phenyl)-1-methoxycarbonyl-ethylcarbamoyl]-2-hydroxy-2-(2-hydroxy-ethyl)-12-oxo-nonadec-4-enoate, Compound D (13.7 g, 19.6 mmol) was dissolved in dichloromethane (274 mL), and then acetic anhydride (4.64 mL, 49.1=mop, triethylamine (2.74 mL, 19.7 mmol), and dimethylaminopyridine (240 mg, 1.96 mmol) were added at 0° C. After stirring for 1.5 hours, the mixture was quenched with water (195 mL) and then separated. The aqueous layer was extracted with dichloromethane (195 mL). The dichloromethane layers were combined, then washed with a saturated aqueous solution (140 mL) of sodium chloride, then dried over anhydrous sodium sulfate, and filtered. The organic layer was concentrated under reduced pressure. The residue was purified on Biotage (silica gel, n-hexane/ethyl acetate) to obtain 11.0 g (14.8 mmol, yield 76%) of No. 5318799 (Compound R).
