To a solution of 5.3 g of the product obtained in Step A (13.9 mmol) in 278 mL of tetrahydrofuran there are added 14 mL of borane-dimethylsulphide complex (BH3Me2S) (27.8 mmol) at ambient temperature. The batch is heated for 4 hours at 80° C. It is allowed to return to ambient temperature and there are then added 7 mL (14 mmol) of BH3Me2S. The reaction mixture is again heated at 80° C. for 2 hours. The tetrahydrofuran is then evaporated off and then there is slowly added methanol and then 5.6 mL of 5M hydrochloric acid (27.8 mmol). The mixture is stirred at ambient temperature overnight, and then at 80° C. for 1 hour. Saturated aqueous NaHCO3 solution is then added to the reaction mixture placed at 0° C. until a pH of 8 is obtained, and extraction with ethyl acetate is then carried out. The organic phase is then dried over magnesium sulphate, and then filtered and evaporated to dryness. The title product is obtained in the form of an oil.
