N-((1S)-1-{[((1S)-3-(Benzyloxy)-2-oxo-1-{[(3S)-2-oxopyrrolidin-3-yl]methyl}propyl)amino]carbonyl}-3,3-dimethylbutyl)-4-methoxy-1H-indole-2-carboxamide (34)
Following the procedure described for the preparation of N-[(1S)-2-[((1S)-3-(benzyloxy)-2-oxo-1-{[(3S)-2-oxopyrrolidin-3-yl]methyl}propyl)amino]-1-(cyclohexylmethyl)-2-oxoethyl]-4-methoxy-1H-indole-2-carboxamide but substituting N1-((1S)-3-(benzyloxy)-2-oxo-1-{[(3S)-2-oxopyrrolidin-3-yl]methyl}propyl)-N2-(tert-butoxycarbonyl)-4-methyl-l-leucinamide and making noncritical variations provided a golden syrup. This material was purified by Biotage MPLC (25 M column, 3% methanol/chloroform) to afford 173 mg (60%) of the title compound as an off-white foam. 1H NMR (400 MHz, DMSO-d6) δ 11.58 (s, 1H), 8.43 (app t, J = 8 Hz, 2H), 7.62 (s, 1H), 7.32 (m, 6H), 7.08 (t, J = 8 Hz, 1H), 7.00 (d, J = 8 Hz, 1H), 6.49 (d, J = 8 Hz, 1H), 4.52 (m, 1H), 4.47–4.35 (m, 4H), 4.22 (d, J = 16 Hz, 1H), 3.87 (s, 3H), 3.05 (m, 2H), 2.28 (m, 1H), 2.06 (m, 1H), 1.93 (m, 1H), 1.64–1.57 (m, 3H), 0.92 (s, 9H); MS (ESI+) for C32H40N4O6m/z 577.2 (M + H)+; anal. calcd for C32H40N4O6·0.33 methanol·0.25 H2O: C, 65.62; H, 7.13; N, 9.47. Found: C, 65.65; H, 6.90; N, 9.58; HRMS (ESI+) calcd for C32H40N4O6 577.3021, found 577.3001.