To a suspension of 6-(thiazolo[4,5-b]pyridin-2-yloxy)-1H-indole-2-carbaldehyde (76 mg, 0.26 mmol) in DCM (3 mL) was added piperidine (0.05 mL, 43 mg, 0.51 mmol), Na(OAc)3BH (65 mg, 0.31 mmol) and the reaction mixture was stirred (rt, 12 h). The reaction mixture was partitioned between saturated NaHCO3 (10 ml) and DCM (20 mL). The organic layer was separated and the aqueous layer was extracted with DCM (2×25 mL). The organic layer was dried, filtered and concentrated in vacuo. The resulting residue was purified by reverse phase HPLC to provide the title compound as a colorless solid (12 mg, 13%). MS (ESI): mass calcd. for C20H20N4OS, 364.1; m/z found, 365.1 [M+H]+. 1H NMR (500 MHz, CDCl3/CD3OD, 10/1): 8.51 (d, J=4.8, 1H), 7.97 (d, J=7.9, 1H), 7.54 (d, J=8.5, 1H), 7.40 (s, 1H), 7.18 (dd, J=7.9, 4.9, 1H), 7.02 (d, J=8.5, 1H), 6.36 (s, 1H), 3.63 (s, 2H), 2.53-2.47 (m, 2H), 2.47-2.36 (m, 2H), 1.76-1.44 (m, 6H).
