Fig. 5: Epimerization property.

a The transformation from (+)-10aS-1 to (–)-10aR-1 and 3 in MeOH with 0.01% NaOH. b The plausible mechanism of racemization for 1.
a The transformation from (+)-10aS-1 to (–)-10aR-1 and 3 in MeOH with 0.01% NaOH. b The plausible mechanism of racemization for 1.