Diethyl Ether → HCID 10888757, compound

Participants

Reaction Steps

Methyl 1-(S-[4-tert-butoxycarbonyl)-4-(tert -butoxycarbonylamino)]butanoyl)indoline-5-acetate 7. Crude 3 (327 mg, 1.9 mmol) was prepared as described above (see compound 4), dissolved in dry MeCN (30 mL) and treated with DMAP (611 mg, 5 mmol) and N-tert-BOC-L-glutamic acid α-tert-butyl ester (607 mg, 2 mmol), followed by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (422 mg, 2.2 mmol). The mixture was stirred at rt for 18 h, then evaporated and the residue was dissolved in EtOAc and washed successively with 0.5 M aq. HCl, saturated aq. NaHCO3 and brine, dried and evaporated to give a viscous oil. Flash chromatography [EtOAc-hexanes (55:45)] and trituration with ether gave. 6 as white crystals (626 mg, 69%), mp 80-81° C. (EtOAc-hexanes); IR: νmax/cm−1; 3340, 1730, 1680, 1655, 1625; 1H NMR: δH (400 MHz) 8.15 (d, J=8 Hz, 1H), 7.07-7.11 (m, 2H), 5.23 (d, J=6.9 Hz, 1H), 4.22 (m, 1H), 4.03 (2×t, J=8.5 Hz, 2H; rotamers), 3.68 (s, 3H), 3.57 (s, 2H), 3.17 (t, J=8.5 Hz, 2H), 2.43-2.59 (m, 2H), 2.18-2.31 (m, 1H), 1.98-2.07 (m, 1H), 1.47 (s, 9H) and 1.41 (s, 9H). Anal. Calcd for C25H36N2O7: C, 63.01; H, 7.61; N, 5.88. Found: C, 63.08; H, 7.81; N, 5.64.

Provenance & Evidence