Reaction Steps
To a solution of (2S)-2-(tert-butoxy)-2-[(20S)-16-chloro-4,20,26-trimethyl-11,19,25-trioxa-1,5,7,8-tetraazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13,15,17,22-octaen-3-yl]acetic acid (0.020 g, 0.032 mmol) in ethanol (1 mL) was added Hoveyda-Grubbs catalyst 2nd generation (4.00 mg, 6.38 μmol). Sodium borohydride (6.03 mg, 0.159 mmol) was added and the mixture was stirred at rt. After 30 min, the reaction was quenched by careful addition of water. The product was extracted with EtOAc, dried (Na2SO4), filtered and concentrated. The crude material was purified via preparative HPLC to afford (2S)-2-(tert-butoxy)-2-[(20S)-16-chloro-4,20,26-trimethyl-11,19,25-trioxa-1,5,7,8-tetraazapentacyclo[24.2.2.16,9.02,7.013,18]hentriaconta-2,4,6(31),8,13,15,17-heptaen-3-yl]acetic acid (6.1 mg, 9.70 μmol, 30.4% yield). 1H NMR (500 MHz, DMSO-d6) δ 7.32 (d, J=8.1 Hz, 1H), 7.06 (s, 1H), 6.94 (d, J=8.1 Hz, 1H), 6.48 (s, 1H), 5.63 (br. S., 1H), 4.84 (d, J=12.5 Hz, 1H), 4.69-4.48 (m, 4H), 4.32 (t, J=11.9 Hz, 1H), 3.65 (br. S., 1H), 3.35-3.22 (m, 4H), 2.74 (s, 3H), 2.02-1.40 (m, 10H), 1.26-0.95 (m, 15H). LCMS (M+H) calcd for C33H46ClN4O6: 629.31. found: 629.4.
