Following the procedure described for the preparation of (3S)-3-({N-[(4-methoxy-1H-indol-2-yl)carbonyl]-l-leucyl}amino)-2-oxo-4-[(3S)-2-oxopyrrolidin-3-yl]butyl acetate but substituting pivalic acid and making noncritical variations provided a crude product. This material was purified by Biotage MPLC (25 M, 2.5–4.5% methanol/dichloromethane) to afford 152 mg (78%) of the title compound. 1H NMR (400 MHz, DMSO-d6) δ 11.58 (s, 1H), 8.56 (d, J = 7.8 Hz, 1H), 8.44 (d, J = 7.8 Hz, 1H), 7.64 (s, 1H), 7.36 (s, 1H), 7.08 (t, J = 8.0 Hz, 1H), 6.99 (d, 1H), 6.49 (d, J = 7.6 Hz, 1H), 4.84 (s, 1H), 4.77–4.94 (m, 1H), 4.34–4.51 (m, 2H), 3.87 (s, 3H), 3.02–3.16 (m, 2H), 1.91–2.36 (m, 3H), 1.48–1.78 (m, 5H), 1.16 (s, 9H), 0.94 (d, J = 6.3 Hz, 3H), 0.89 (d, J = 6.3 Hz, 3H); MS (ESI+) for C29H40N4O7m/z 557.2 (M + H)+. Anal. calcd for C29H40N4O7·0.76 H2O: C, 61.07; H, 7.34; N, 9.82. Found: C, 61.14; H, 7.63; N, 9.59.