A 3.0 M diethyl ether solution of ethylmagnesium bromide (7.3 ml, 21.8 mmol) is added under N2 at 0° C. to a 95 ml tetrahydrofuran solution of N-benzenesulfonyl-3-iodo-5,7-difluoro-indole (8.4 g, 20 mmol). The resulting mixture is stirred for 20 minutes at 0° C., allowed to warm to room temperature over 20 minutes, then recooled to 0° C. A 20 ml tetrahydrofuran solution of (S)N,N dibenzyl-2-aminopropanal (Syn. Lett., 1997,2, 223-224, 5.1 g, 22 mmol) is added to the reaction mixture and the resulting mixture is stirred 1 hour as it warmed to room temp. The reaction is quenched with aqueous NH4Cl, extracted with ethyl acetate, washed with brine, dried (Na2SO4), filtered, concentrated, and the residue is purified by flash chromatography (SiO2, ethyl acetate/hexane gradient) to yield 8.4 g of 2-(N,N-dibenzylamino)-1-(1-benzenesulfonyl-5,7-difluoro-1H-indol-3-yl)-propan-1-ol. (77%)
