A mixture of 4-cyclopropylmethoxy-N—((S)-6-formyl-1,2,3,4-tetrahydronaphthalen-2-yl)-benzamide (2.70 g), methyl iodide (0.534 ml) and DMF (100 ml) was admixed at 0° C. with sodium hydride (55% in paraffin oil; 0.34 g) in portions. After 15 minutes, the reaction mixture was poured into saturated ammonium chloride solution and extracted with ethyl acetate. The organic phase was dried over sodium sulfate and concentrated. The residue was chromatographed on silica gel (eluent: 30% n-heptane in ethyl acetate). The product was thus obtained with the molecular weight of 363.46 (C23H25NO3); MS (ESI): 364 (M+H+).
