Reaction Steps
A mixture of ethyl (2S)-2-(tert-butoxy)-2-{4,25-dimethyl-11,24-dioxa-1,5,7,8-tetraazapentacyclo[23.2.2.16,9.02,7.013,18]triaconta-2,4,6(30),8,13(18),14,16-heptaen-3-yl}acetate (37 mg, 0.062 mmol) and NaOH (0.312 mL, 0.312 mmol) in EtOH (2 mL) was refluxed for 2 h. It was then filtered and purified by preparative HPLC to obtain (2S)-2-(tert-butoxy)-2-{4,25-dimethyl-11,24-dioxa-1,5,7,8-tetraazapentacyclo[23.2.2.16,9.02,7.013,18]triaconta-2,4,6(30),8,13(18),14,16-heptaen-3-yl}acetic acid (21 mg, 0.037 mmol, 59.6% yield) as a white solid. 1H NMR (500 MHz, DMSO) δ 7.29 (d, J=7.7 Hz, 1H), 7.26-7.19 (m, 2H), 7.17-7.11 (m, 1H), 6.53 (s, 1H), 5.71 (s, 1H), 4.74-4.58 (m, 4H), 4.50-4.42 (m, 1H), 3.68-3.20 (m, 4H), 2.82-2.75 (m, 1H), 2.66 (d, J=8.4 Hz, 2H), 2.51 (s, 3H), 1.90-1.81 (m, 2H), 1.71-1.51 (m, 8H), 1.19 (s, 3H), 1.15 (s, 9H). LCMS (M+1)=565.3.
