Reaction Steps
To a stirred solution of methyl (2S)-2-hydroxy-2-[(22S)-4,17,22,28-tetramethyl-21,27-dioxa-1,5,7,8-tetraazahexacyclo[26.2.2.16,9.110,14.02,7.015,20]tetratriaconta-2,4,6(34),8,10(33),11,13,15(20),16,18-decaen-3-yl]acetate (40 mg, 0.067 mmol) in DCM (2 mL) and 1-methylcyclobutyl acetate (599 mg, 4.68 mmol) at rt was added 70 wt % perchloric acid (0.017 mL, 0.200 mmol). After 3 h, the reaction mixture was diluted with DCM (25 mL), carefully quenched with sat. NaHCO3 (5 mL), organic layer separated and washed with brine (10 mL), dried (Na2SO4), filtered and concentrated to give yellow paste. The crude was then tretated with 1N NaOH (0.334 mL, 0.334 mmol) in MeOH (1 mL) at 75° C. for 3 h. Mixture was then cooled and purified by prep HPLC to afford (2S)-2-(1-methylcyclobutoxy)-2-[(22S)-4,17,22,28-tetramethyl-21,27-dioxa-1,5,7,8-tetraazahexacyclo[26.2.2.16,9.110,14.02,7.015,20]tetratriaconta-2,4,6(34),8,10(33),11,13,15(20),16,18-decaen-3-yl]acetic acid (15.8 mg, 0.024 mmol, 36.2% yield). 1H NMR (500 MHz, DMSO-d6) δ 8.52 (s, 1H), 7.91 (d, J=7.9 Hz, 1H), 7.51 (t, J=7.6 Hz, 1H), 7.33 (d, J=7.6 Hz, 1H), 7.17-7.11 (m, 2H), 7.08 (s, 1H), 7.05 (d, J=8.2 Hz, 1H), 5.49 (s, 1H), 4.62 (d, J=5.5 Hz, 1H), 4.45 (t, J=12.2 Hz, 1H), 3.61-3.53 (m, 1H), 3.40-3.20 (m, 7H), 2.83 (d, J=10.4 Hz, 1H), 2.29 (s, 3H), 2.22 (q, J=10.0 Hz, 1H), 2.01-1.86 (m, 4H), 1.82 (br. s., 1H), 1.70-1.62 (m, 5H), 1.58-1.41 (m, 4H), 1.28 (s, 3H), 1.17 (s, 3H), 1.07 (d, J=5.8 Hz, 3H). LCMS (M+H)=653.6.
