反应详情

15.16 g of (2S,4S)-2-carbamoyl-4-(4-methoxybenzylthio)-1-methylpyrrolidine [prepared as described in step (i) above] were dissolved in 170 ml of 2N aqueous hydrochloric acid, and the solution was stirred in a bath kept at 110° C. for 3.5 hours. At the end of this time, the reaction mixture was cooled to room temperature, and its pH was adjusted to a value of by the addition of sodium carbonate. The mixture was then concentrated by evaporation under reduced pressure, after which it was allowed to stand in a refrigerator precipitate crystals. The precipitated crystals were collected by filtration and washed with a small amount of cold water. They were then dried, to give 10.4 g of the title compound. The mother liquor was then concentrated by evaporation under reduced pressure, and the residue was subjected to column chromatography through CHP20P (75-150μ, Mitsubishi Chemical Industries, Ltd.), using 50% v/v aqueous methanol as the eluent, to afford a further 3.7 g of the title compound, as crystals melting an 185°-187.5° C.

1. concentrationThe mixture was then concentrated by evaporation under reduced pressure
2. filtrationThe precipitated crystals were collected by filtration
3. washwashed with a small amount of cold water
4. customThey were then dried