The alcohol 247 (0.083 g, 0.147 mmol) was dissolved in 20 mL of dichloromethane and to it dimethylaminobutyric acid hydrochloride (0.030 g, 0.176 mmol) was added followed by Hunig's base (0.045 g, 0.44 mmol) and DMAP (2 mg). To this mixture EDCI (0.034 g, 0.176 mmol) was added and the reaction mixture was stirred at room temperature overnight and the TLC (silica gel, 10% MeOH in CH2Cl2) showed complete disappearance of the starting alcohol. The reaction mixture was diluted with CH2Cl2 (40 mL) and washed with saturated NaHCO3 (50 mL), water (60 mL) and brine (60 mL). The combined organic layers were dried over anhyd. Na2SO4 and solvents were removed in vacuo. The crude product thus obtained was purified by Combiflash Rf purification system (40 g silicagel, 0-10% MeOH in CH2Cl2) to isolate the pure product (0.062 g, 62%) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ 5.74-5.58 (m, 2H), 5.51 (dtt, J=9.7, 6.8, 1.3 Hz, 2H), 4.95-4.75 (m, 1H), 4.61 (d, J=6.8 Hz, 4H), 2.35-2.24 (m, 8H), 2.22 (d, J=7.9 Hz, 6H), 2.09 (q, J=6.9 Hz, 4H), 1.83-1.72 (m, 2H), 1.60 (dd, J=14.4, 7.2 Hz, 4H), 1.49 (d, J=5.7 Hz, 4H), 1.41-1.13 (m, 30H), 0.88 (t, J=6.9 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 173.72, 173.36, 135.40, 123.35, 74.12, 60.18, 58.95, 45.46, 34.30, 34.11, 32.45, 31.67, 29.38, 29.35, 29.17, 29.07, 28.84, 27.53, 25.28, 24.93, 23.16, 22.59, 14.06. MW calc. for C41H75NO6 (MH+): 678.04. found: 678.5.
