To a stirred solution of N-[(methyloxy)carbonyl]-L-alanine (22.5 mg, 0.153 mmol, prepared according to the procedure provided in WO2003055474) in DMF (2 mL) were added TEA (15.5 mg, 0.153 mmol) and HATU (58.2 mg, 0.153 mmol). After ˜3 min stirring, methyl [(1S)-1-({(2S)-2-[4-(4′-{2-[(3S)-6,10-dioxa-2-azaspiro[4.5]dec-3-yl]-1H-imidazol-4-yl}-4-biphenylyl)-1H-imidazol-2-yl]-1-pyrrolidinyl}carbonyl)-2-methylpropyl]carbamate (Example 19) (100 mg, 0.153 mmol) was introduced. After stirred for additional 2 hrs at rt, the reaction mixture was directly loaded to RP HPLC, eluting with 5 to 80% acetonitrile/water (0.2% NH3H2O (conc.)), to give methyl ((1S)-1-methyl-2-{(3S)-3-[4-(4′-{2-[(2S)-1-((2S)-3-methyl-2-{[(methyloxy)carbonyl]amino}butanoyl)-2-pyrrolidinyl]-1H-imidazol-4-yl}-4-biphenylyl)-1H-imidazol-2-yl]-6,10-dioxa-2-azaspiro[4.5]dec-2-yl}-2-oxoethyl)carbamate (Example 5) as solid (36 mg, yield: 29%). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 10.04-11.11 (m, 2H) 7.37-8.02 (m, 8H) 7.18-7.36 (m, 2H) 5.60 (br. s., 2H) 5.17-5.40 (m, 2H) 3.17-4.73 (m, 14H) 2.79-3.19 (m, 1H) 2.45-2.81 (m, 1H) 2.29-2.45 (m, 1H) 1.49-2.29 (m, 8H) 1.22-1.47 (m, 3H) 0.73-1.16 (m, 6H). HRMS: (M+H)+ calcd: 783.3830; found: 783.3832.
