The title compound was prepared in 71% yield from 10.31 g of the thione of Example 9 upon heating with 38.15 ml of tri-n-butyl tin hydride and 1.16 g of azobisisobutyronitrile (AIBN) in 142 ml of toluene at reflux temperature for one hour. The product was isolated by adding water to the cooled reaction mixture, separating the layers, washing the organic layer with 1N hydrochloric acid and a saturated sodium chloride solution, drying over magnesium sulfate, concentrating in vacuo, and purifying the residue by chromatography over silica gel eluting with a 10-50% hexane in ethyl acetate gradient. The purified product had a melting point of 142-144° C.
