Example 3: General procedure for the synthesis of ((R)-4-((3R,5S,7R,8R,9S,10S,12S,13R,14S,17R)-3,7,12-trihydroxy-10,13-dimethylhexadecahydro-1H-cyclopenta[a]phenanthren[a]ethene-17-yl)pentanoyl)glycine from glycocholic acid ethyl ester (GCAEE):
1. 1.89 g of NaOH was dissolved in 189 ml of water at ambient temperature in a clean 1 liter dry glass flask and stirred until completely dissolved.
2. 16.9 g of purified wet GCAEE was added to the above solution and the suspension was stirred at 20 to 28°C for about 12 hours.
3. Adjust the pH of the clarified solution to between 7.0 and 7.5 using 50 ml of 1N HCl.
4. wash the aqueous solution twice with 75 ml of ethyl acetate at 35 to 40 °C.
5. Heat the separated aqueous solution under vacuum to remove the ethyl acetate.
6. the resulting aqueous solution was diluted with 100 ml of water, heated at 35 to 40 °C and the pH was adjusted to between 2.0 and 2.5 with 1N HCl to precipitate pure GCA.
7. The wet product was dried under vacuum at 50 to 60 °C to give 14 g of the sesquihydrate product in 92.3% dry yield.
8. TLC analysis showed that the purity of CA was less than 0.4%, GGCAEE was less than 0.1%, total other impurities were less than 0.2%, and no glycine was observed.
