Synthesis of sodium (4bS,8R,8aR)-8-carboxy-2-isopropyl-4b,8-dimethyl-4b,5,6,7,8,8a,9,10,10-octahydro-phenanthrene-3-sulfonate from (1R,4aS,10aR)-7-isopropyl-1,4a-dimethyl-6-sulfo-1,2,3,4,4a,9,10,10a-octahydro-phenanthrene-1-carboxylic acid The general procedure for the salt was as follows: the feedstock compound (II) (80 g, 0.210 mol) was added to a 25% aqueous solution of sodium isooctanoate (36.6 g, 0.221 mol) and the reaction was stirred for 0.5 to 1 hour. The mixture was then heated until it was completely dissolved and showed clarification, after which it was thermally filtered. The filtrate was cooled to 0°C to 10°C to induce precipitation of a large white solid. The precipitate was separated by filtration and the filter cake was dried under reduced pressure to give the target product (I) as a white solid. The product was characterized as follows: specific spin of +72° (water), moisture content of 18.06%, HPLC purity of more than 99.5%, chemical content of 99.98%, and total yield of 87.5%.
