A solution of the product of example 39 step (i) (0.120 g) together with 2-bromoethyl methyl ether (0.073 ml) and a 1M solution of potassium tert-butoxide in tetrahydrofuran (0.62 ml) in N,N-dimethylformamide (3 ml) was heated at 50° C. for 20 h. Sufficient sodium hydrosulphide was added to give a blue solution and the reaction mixture heated at 80° C. for 4 h. The reaction mixture was cooled, diluted with ethyl acetate and washed with saturated aqueous ammonium chloride. The organic phase was dried over magnesium sulphate, filtered and evaporated. The crude product was purified by chromatography eluting with 1% methanol in dichloromethane, followed by trituration with ethyl acetate to give the title compound as a yellow solid.
