Sodium Thiosulfate → 3-[5-Methanesulfonyl-3-(4-trifluoromethyl-phenyl)-4,5,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-1-yl]-propionaldehyde

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Reaction Steps

Dess-Martin periodinane (3.45 g, 8.2 mmol) was added to a solution of 3-[5-methanesulfonyl-3-(4-trifluoromethyl-phenyl)-4,5,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-1-yl]-propan-1-ol (3.0 g, 7.4 mmol) in CH2Cl2 (20 mL) at 0° C. under N2. After 15 min, the reaction was allowed to warm to room temperature and stirred for another 1.5 h. The reaction was diluted with Et2O (60 mL) and 20% aq. NaHCO3 (35 mL) was added slowly (caution! rapid gas evolution). Then Na2S2O3 was added and stirred at room temperature for 30 min. The layers were separated and the aqueous portion was extracted with Et2O (2×30 mL). The combined organic extracts were washed with brine, dried (Na2SO4) and concentrated. MPLC (silica, 1-10% MeOH/CH2Cl2) afforded 2.53 g of the desired aldehyde in 85% yield. MS (electrospray): exact mass calculated for C17H18F3N3O3S, 401.11; m/z found, 402.1 [M+H]. 1H NMR (400 MHz, CDCl3): 9.82 (s, 1H), 7.63 (d, J=8.4 Hz, 2H), 7.58 (d, J=8.4 Hz, 2H), 4.68 (s, 2H), 4.25 (t, J=6.1 Hz, 2H), 3.63 (t, J=5.8 Hz, 4H), 3.14 (t, J=6.1 Hz, 2H), 2.92 (t, J=5.8 Hz, 2H), 2.81 (s, 3H).

Provenance & Evidence