2,2-Dimethyl-1-(2-hydroxyethylidene)-7-methoxy-3-(N-methyl-p-toluenesulphonamido)-1,2,3,4-tetrahydronaphthalene (15.5 g), dissolved in 250 ml of methanol, containing 2.2 ml of triethylamine, is submitted to catalytic hydrogenation, at atmosphere pressure and room temperature, the catalyst being 2.3 g 5% palladium on charcoal. The calculated amount of hydrogen is taken up within one hour. The catalyst is removed by filtration and the solvent by evaporation in vacuo. The residue is dissolved in chloroform and the solution is freed from basic material by means of washing with dilute hydrochloric acid and water, respectively. The dried solution is then concentrated in vacuo leaving a mixture containing two stereoisomers of the desired product. This mixture is suitable for further elaboration as described in example 13.
