60 ml (96 mmol) of a 1.6 N solution of n-butyllithium in n-hexane were added slowly, under a nitrogen atmosphere and at −55° C., to a solution of 18 g (96 mmol) of 3-bromoanisole in 200 ml of dry THF. After 2 h the solution was added via cannula to a solution of 19.7 g (96 mmol) of N,N-diethyl-4-formylbenzamide in 200 ml of dry THF. The reaction mixture was allowed to warm up to room temperature overnight, then it was quenched with NH4Cl saturated solution. The aqueous phase was extracted with Et2O. The organic phase dried over Na2SO4 and the solvent removed in vacuo. The crude reaction mixture was employed in the next synthetic step without further purification. A solution of 15.3 ml of DMSO in 45 ml of CH2Cl2 was added slowly, under a nitrogen atmosphere and at −55 ° C., to a solution of 9 ml of oxalyl chloride in 200 ml of CH2Cl2. After 2 min. the crude reaction mixture obtained in the preceding step and dissolved in 90 ml of CH2Cl2 was added, followed, after 15 min. by 65 ml of Et3N. The reaction mixture was allowed to warm up to room temperature in 2 h, then it was quenched with 500 ml of H2O. The organic phase is separated and washed with 10% HCl solution, then dried over Na2SO4 and the solvent removed in vacuo. The crude reaction mixture was purified by flash chromatography, eluting with Et2O/hexane 9:1 respectively, yielding 12.5 g of the title compound.
