The synthetic challenge for the total synthesis of pyrrovobasine (1) is the epimerization of the thermodynamically stable methyl ester stereochemistry in 14 to the kinetic product methyl ester 16. We first tried to epimerize 14 under different basic conditions, but the desired kinetic product methyl ester 16 was not observed under any of the conditions. On the other hand, Zhang and Yang et al. reported the epimerization of the thermodynamically stable methyl ester using Ir-catalyzed photo-epimerization. Therefore, 14 was treated with LDA and iodine to give 15, which was found to be unstable and used immediately for the next reaction without purification. Then 15 was successfully converted to 16 by UV irradiation at 365 nm in the presence of an Ir-catalyst at -50 ºC followed by deprotection of the Boc group. Although this epimerization procedure works well, the resulting kinetically dominated product 16 was difficult to separate from the thermodynamically dominated product methyl ester, which was also generated in situ during the photo-epimerization reaction from 15. Therefore, the crude product 16 was used in the next reaction without further purification.