4-(4-Trifluoromethylphenyl)benzaldehyde (85.43 g, 0.3414 mol) (Int. D2) and 4A molecular sieve (400 g, predried at 120° C.) were suspended in dichloromethane (1.4 L), then N,N-diethylethylenediamine (47.97 ml, 0.3414 mol) was added. The mixture was left at room temperature for 16 h with occasional shaking, then the sieves were filtered off and washed with dichloromethane. The combined filtrates were evaporated to a yellow solid and dried under high vacuum. This material (114.3 g, 0.328 mol) in ethanol (1 L) was cooled in an ice bath, and sodium borohydride (12.41 g, 0.328 mol) was added under argon with stirring. Hydrogen evolution was observed. After 30 min the ice bath was removed, and the cloudy yellow solution was left to stand at room temperature for 16 h. The solvent was removed in vacuo, water and brine were added, and the mixture was extracted 3× with dichloromethane. The combined extracts were dried over potassium carbonate and evaporated to give the title compound as a yellow solid, (112.1 g, 98%). 1H-NMR (CDCl3) δ 7.66 (4H, s), 7.53-7.56 (2H, m), 7.40-7.44 (2H, m), 3.86 (2H, s), 2.47-2.75 (9H, m), 0.96-1.10 (6H, m); MS(APCI+) found (M+1)=351, C20H25F3N2 requires 350.
