Reaction Steps
A mixture of ethyl (2S)-2-(tert-butoxy)-2-[(24S)-4,24,30-trimethyl-11,23,29-trioxa-1,5,7,8-tetraazahexacyclo[28.2.2.16,9.02,7.013,22.016,21]pentatriaconta-2,4,6(35),8,13(22),14,16(21),17,19-nonaen-3-yl]acetate (47 mg, 0.070 mmol) and NaOH (0.070 mL, 0.070 mmol) in EtOH (2 mL) was refluxed for 2 h. It was then cooled to rt and purified by preparative HPLC to obtain (2S)-2-(tert-butoxy)-2-[(24S)-4,24,30-trimethyl-11,23,29-trioxa-1,5,7,8-tetraazahexacyclo[28.2.2.16,9.02,7.013,22.016,21]pentatriaconta-2,4,6(35),8,13(22),14,16(21),17,19-nonaen-3-yl]acetic acid (31.3 mg, 0.046 mmol, 66.0% yield) as a white solid. 1H NMR (500 MHz, DMSO-d6) δ 8.12 (d, J=8.4 Hz, 1H), 7.87 (d, J=8.8 Hz, 1H), 7.63 (d, J=8.4 Hz, 1H), 7.53-7.43 (m, 3H), 6.58 (s, 1H), 5.82 (s, 1H), 4.83-4.75 (m, 2H), 4.75-4.67 (m, 1H), 4.58 (d, J=10.6 Hz, 1H), 4.49-4.35 (m, 2H), 3.74 (t, J=10.8 Hz, 1H), 3.37-3.53 (m, 2H), 3.06 (d, J=9.2 Hz, 1H), 2.64 (d, J=11.7 Hz, 1H), 2.50 (s, 3H), 1.95 (d, J=13.2 Hz, 2H), 1.88-1.45 (m, 8H), 1.20 (s, 3H), 1.16 (s, 9H), 1.07 (d, J=5.9 Hz, 3H). LCMS (M+1)=645.3.
