2M Trimethylaluminium (1.250 ml, 2.50 mmol) in toluene, was added dropwise to a stirred solution of ethyl 5-(4-methylpiperazin-1-yl)thiophene-2-carboxylate (0.254 g, 1 mmol) and 5-[2-(3,5-dimethoxyphenyl)ethyl]-2H-pyrazol-3-amine (0.247 g, 1.00 mmol) in toluene (7.14 ml) at 20° C. under nitrogen. The reaction mixture was stirred at ambient temperature for 16 h and then heated at 65° C. for 24 h. Ethyl acetate (5 mL) was added to the reaction mixture followed by a solution of potassium sodium tartrate (5 mL, 20% aqueous). More ethyl acetate (50 mL) and water (25 mL) was added and the mixture was filtered through celite. The filtrate was transferred to a separating funnel and the aqueous layer removed. The ethyl acetate layer was washed with saturated brine and then dried over magnesium sulphate. After filtration the solvent was evaporated to give the crude product as a yellow solid. The crude product was purified by preparative HPLC, using decreasingly polar mixtures of water (containing 1% NH3) and MeCN as eluents. Fractions containing the desired compound were evaporated to dryness to afford the title compound (0.154 g, 33.8%) as a white solid.
