Reaction Steps
To a solution of ethyl (2S)-2-(tert-butoxy)-2-[(20S)-15-fluoro-4,20,26-trimethyl-11,19,25-trioxa-1,5,7,8-tetraazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13(18),14,16,22-octaen-3-yl]acetate: (46.1 mg, 0.072 mmol) in ethanol (3 mL) were added (1,3-dimesitylimidazolidin-2-ylidene)(2-isopropoxybenzylidene)ruthenium(VI) chloride (9.04 mg, 0.014 mmol) then sodium borohydride (13.65 mg, 0.361 mmol) and the mixture was stirred at rt. After 10 min, LCMS indicated completion of reaction. The reaction was quenched with water and extracted with EtOAc. The organic phase was dried (Na2SO4), filtered and concentrated. The crude was purified by flash chromatography (Biotage; 0%-100% EtOAc/hexane; 20 CV) to give ethyl (2S)-2-(tert-butoxy)-2-[(20S)-15-fluoro-4,20,26-trimethyl-11,19,25-trioxa-1,5,7,8-tetraazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13,15,17-heptaen-3-yl]acetate (36.5 mg, 0.057 mmol, 79% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ δ 7.15 (dd, J=9.0, 3.2 Hz, 1H), 6.89 (td, J=8.6, 3.2 Hz, 1H), 6.79 (dd, J=8.9, 4.5 Hz, 1H), 6.56 (s, 1H), 5.97 (s, 1H), 4.93 (d, J=12.2 Hz, 1H), 4.75-4.66 (m, 3H), 4.56-4.39 (m, 2H), 4.29-4.15 (m, 2H), 3.97-3.81 (m, 1H), 3.56-3.34 (m, 2H), 3.14 (d, J=11.7 Hz, 1H), 2.83 (d, J=12.2 Hz, 1H), 2.61 (s, 3H), 2.03-1.53 (m, 10H), 1.34-1.13 (m, 18H). LCMS (M+H) calcd for C35H50FN4O6: 641.37. found: 641.6.
