A stock solution of periodic acid/chromium trioxide was prepared according to WO 99/52850 by dissolving periodic acid (11.4 g, 50.0 mmol) and chromium trioxide (23 mg, 1.2 mol %) in wet acetonitrile (0.75% H2O) to a volume of 114 mL. This stock solution (0.6 mL) was added to a solution of (S)-2-tert-butoxy-2-(7-(4-chlorophenyl)-5-methyl-2-(2-(1-methyl-1H-indazol-6-yl)pyridin-4-yl)benzo[d]thiazol-6-yl)ethanol (25 mg, 0.049 mmol) in ACN (3 mL) at room temperature and stirred for one hour. The reaction mixture was quenched with saturated Na2SO3 solution and extracted with EtOAc. The organic layer was dried (MgSO4), filtered, concentrated and purified by reverse phase HPLC (H2O/ACN+0.1% TFA) to give the desired product after lyophilization. LCMS-ESI+: calc'd for C33H30ClN4O3S: 597.2 (M+H+); found: 597.2, 599.2. 1H NMR (400 MHz, CD3OD) δ 8.72 (d, J=5.3 Hz, 1H), 8.46 (s, 1H), 8.43 (s, 1H), 8.14-8.08 (m, 2H), 7.94-7.87 (m, 2H), 7.73-7.63 (m, 2H), 7.61-7.54 (m, 3H), 5.26 (s, 1H), 4.10 (s, 3H), 2.63 (s, 3H), 0.97 (s, 9H).
