Reaction Steps
A mixture of ethyl (2S)-2-(tert-butoxy)-2-[(20S)-4,12,16,20,26-pentamethyl-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-heptaen-3-yl]acetate (10 mg, 0.015 mmol) and sodium hydroxide (0.077 mL, 0.077 mmol) in EtOH (2 mL) was refluxed for 2 h. It was then cooled to rt and purified by preparative HPLC to isolate the first eluting isomer (2S)-2-(tert-butoxy)-2-[(12S,20S)-4,12,16,20,26pentamethyl-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-heptaen-3-yl]acetic acid (4.0 mg, 41.8%) as a white solid. 1H NMR (500 MHz, DMSO-d6) δ 7.24 (d, J=7.7 Hz, 1H), 6.82 (s, 1H), 6.74 (d, J=7.7 Hz, 1H), 6.31 (s, 1H), 5.56-5.43 (m, 2H), 4.63-4.39 (m, 4H), 3.66-3.51 (m, 4H), 2.85 (d, J=11.0 Hz, 1H), 2.48 (s, 3H), 2.28 (s, 3H), 1.94-1.86 (m, 2H), 1.75-1.48 (m, 8H), 1.28 (d, J=6.2 Hz, 3H), 1.19 (d, J=8.4 Hz, 6H), 1.14 (s, 9H). LCMS (M+1)=623.3.
