4-Methoxybenzenesulfonyl chloride → 3-[5-Methoxy-1-(4-methoxy-benzenesulfonyl)-1H-indol-3-yl]-propionic acid methyl ester

To a cooled solution (0° C.) of indole-3-propionic acid methyl ester 142 (0.110 g, 0.42 mmol) in DMF (3 mL) was added sodium hydride (60%; 0.030 g; 0.75 mmol) was added in one portion and stirred for 30 min followed by the addition of 4-methoxybenzenesulfonyl chloride (0.200 g; 1.0 mmol). The reaction was allowed to warm up to room temperature and stirred for 16 h, subjected to aqueous work up, and product was extracted with ethyl acetate. The ethyl acetate layer was washed with brine, dried over anhydrous sodium sulfate, evaporated under reduced pressure, and purified by flash-chromatography (silica gel; 85% n-hexane-15% ethyl acetate) to afford the methyl ester 120 as an oil (M+1=432.4). The methyl ester 120 was then taken on toward generation of the product.