Hydrochloric Acid → Ethyl trans-4-hydroxy-L-prolinate hydrochloride

Participants

Reaction Steps

Trans-4-hydroxy-L-proline was treated with EtOH and HCl gas, and the mixture was evaporated to give trans-4-hydroxy-L-proline ethyl ester hydrochloride. This product was treated with TsCl in pyridine, to give after aqueous workup N-(toluene-4-sulfonyl)-trans-4-(O-(toluene-4-sulfonyl))-L-proline ethyl ester. This product was treated with PhSH and DBU in DMF to give after aqueous workup and flash chromatography on silica gel, N-(Toluene-4-sulfonyl)-cis-4-(phenylthio)-L-proline ethyl ester. This product was treated with NaOH in CH3OH and H2O, to give after acidification, extraction, drying with MgSO4, filtration and evaporation, N-(toluene-4-sulfonyl)-cis-4-(phenylthio)-L-proline. This product was treated with HCl.Phe-OMe, BOP, and NMM in DMF, to give, after aqueous workup and flash chromatography, N-(toluene-4-sulfonyl)-cis-4-(phenylthio)-Pro-Phe-OMe. This product was treated with NaOH in CH3OH and H2O, to give, after acidification, extraction, drying with MgSO4, filtration and evaporation, the title compound as a clear oil.

Provenance & Evidence