28 mg of 50% sodium hydride and 3 ml of dimethylformamide are introduced, agitation is carried out at ambient temperature for 5 minutes, 170 mg of the product obtained in Stage 3 above is added and the whole is left under agitation for 20 minutes until the release of hydrogen has stopped. 202 mg of O-trimethylsilyl-4-iodo-n-butanol is then added and the reaction medium is left under agitation for 2 hours. After hydrolysis using saturated ammonium chloride, extraction is carried out with ethyl acetate. The organic phases are combined, washed with water, dried, filtered and concentrated. The residue is solubilized in 10 ml of methanol and 0.5 ml of 2N hydrochloric acid is added. After agitation for 5 minutes, the solution is neutralized by the addition of saturated sodium hydrogen carbonate and extraction is carried out with ethyl acetate. The organic phases are combined, dried, filtered and concentrated. After chromatography on silica eluting with methylene chloride-acetone: 9-1, 158 mg of expected product (white solid) is obtained. M.p.=145° C.
