Reaction Steps
A mixture of ethyl (2S)-2-(tert-butoxy)-2-[(20S)-11-cyclopropyl-4,16,20,26-tetramethyl-19,25-dioxa-1,5,7,8,11-pentaazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13(18),14,16-heptaen-3-yl]acetate (70 mg, 0.104 mmol) and NaOH (0.311 mL, 0.311 mmol) in EtOH (2 mL) was refluxed for 2 h. It was then cooled to rt, purified by preparative HPLC to obtain (2S)-2-(tert-butoxy)-2-[(20S)-11-cyclopropyl-4,16,20,26-tetramethyl-19,25-dioxa-1,5,7,8,11-pentaazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13(18),14,16-heptaen-3-yl]acetic acid (42 mg, 0.065 mmol, 62.6% yield) as a white solid. 1H NMR (500 MHz, DMSO-d6) δ 7.12 (d, J=7.3 Hz, 1H), 6.76 (s, 1H), 6.64 (d, J=7.7 Hz, 1H), 6.37 (s, 1H), 5.61 (s, 1H), 4.52 (br. s., 1H), 4.34 (t, J=12.3 Hz, 1H), 4.04 (d, J=14.3 Hz, 1H), 3.92 (d, J=15.0 Hz, 1H), 3.81 (d, J=14.3 Hz, 1H), 3.72 (d, J=15.0 Hz, 1H), 3.68-3.59 (m, 1H), 3.50-3.29 (m, 3H), 2.79-2.71 (m, 1H), 2.48 (s, 3H), 2.27 (s, 3H), 1.97 (br. s., 1H), 1.91 (s, 1H), 1.83 (d, J=12.8 Hz, 1H), 1.78-1.43 (m, 8H), 1.20 (d, J=5.9 Hz, 3H), 1.17 (s, 3H), 1.14 (s, 9H), 0.45 (d, J=5.5 Hz, 1H), 0.35 (d, J=4.8 Hz, 2H), 0.27 (br. s., 1H). LCMS (M+1)=648.5.
