General procedure for the synthesis of 5-trifluoromethylpyridine-2-carboxaldehyde from 5-trifluoromethylpyridine-2-methanol: A dichloromethane (10 mL) solution of Example 34B (3.89 g, 22.0 mmol) was added to a dichloromethane (10 mL) solution of Dess-Martin periodinane (1 ,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodioxo heterocyclopentan-3(1H)-one, 10.3 g, 24.2 mmol) in a solution of dichloromethane (73 mL). The reaction mixture was stirred at room temperature for about 20 minutes under nitrogen protection until a solid was formed. The reaction mixture was diluted with 50 mL of dichloromethane and about 30 mL of saturated sodium bicarbonate solution was carefully added to quench the reaction. The undissolved solid was removed by filtration and the filtrate was transferred to a partition funnel. The aqueous phase was extracted with dichloromethane and the combined organic layers were washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to 50 mL. The concentrate was purified by passing it through a silica gel column (Analogix 40 x 150 mm) using 25% to 50% ethyl acetate/hexanes as eluent. 2.86 g (74% yield) of 5-trifluoromethylpyridine-2-carboxaldehyde was finally obtained as a clear oil, which solidified on standing.1H NMR (300 MHz, CDCl3) δ 10.15 (s, 1H), 9.06 (m, 1H), 8.15 (m, 1H), 8.09 (d, J=8.1 Hz, 1H).
