A mixture of (S)—N,N-dibutyl-1-(2-(3-(((tert-butyldimethylsilyl)oxy)methyl)-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)-4-(phenylsulfonamido)phenyl)-5-methyl-1H-pyrazole-3-carboxamide and (S)—N,N-dibutyl-1-(2-(3-(((tert-butyldimethylsilyl)oxy)methyl)-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)-4-(N-(phenylsulfonyl)phenylsulfonamido)phenyl)-5-methyl-1H-pyrazole-3-carboxamide (0.21 g, 0.272 mmol) in THF (2.1 mL) was treated with 3N HCl (0.62 mL) at RT for 10 min. The reaction mixture was diluted with water (20 mL), the pH was adjusted to about 8 using aq. NaHCO3 solution and extracted with EtOAc (100 mL). The organic layer was washed with water (50 mL), brine (50 mL), dried over sodium sulphate and concentrated invacuo. The residue was purified on silica gel (100-200 mesh) to afford the title compound as a hygroscopic solid, 0.025 g (14%). Rf=0.38 (5% MeOH in DCM); 1H NMR (400 MHz, DMSO-d6): δ 10.85-10.70 (m, 1H, D2O exchangeable), 7.78-6.60 (m, 12H), 6.50-6.20 (m, 1H), 5.00-3.60 (m, 4H), 3.60-2.40 (m, 8H), 2.25-2.00 (m, 3H), 1.60-0.50 (m, 14H); LC-MS: m/z 658.4 (M+H), HPLC: 95.08% (RT=9.403 min., method I).
