Sodium hydride (60% oil dispersion, 0.009 g) was added to a stirred and cooled solution of ethyl 6-(benzenesulphonylmethyl)-3-ethyl-2-methoxybenzoate (Intermediate 20, 0.075 g) in DMF (1 ml) at 0° C. under an atmosphere of nitrogen. After stirring for 15 minutes iodomethane (0.014 ml) was added and the resultant mixture was stirred at room temperature for 1 hour. Ammonium chloride (saturated aqueous solution) was added followed by water and the mixture was extracted with ethyl acetate, washed with water, brine, dried (MgSO4) and filtered. The filtrate was evaporated to dryness and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and cyclohexane with a gradient of 0-20% to give ethyl 6-(1-benzenesulphonylethyl)-3-ethyl-2-methoxybenzoate (0.063 g) as a colourless oil.
