Ammonia → 1-(3-Mercapto-1-oxopropyl)-L-proline
Reaction equation
C([O:5][C:6](=[O:20])[C@@H:7]1[CH2:11][CH2:10][CH2:9][N:8]1[C:12](=[O:19])[CH2:13][CH2:14][S:15]C(=O)C)(C)(C)C.N>>[SH:15][CH2:14][CH2:13][C:12]([N:8]1[CH2:9][CH2:10][CH2:11][C@H:7]1[C:6]([OH:20])=[O:5])=[O:19]Participants
3
Procedure
The product of Step (a), 3-acetylthiopropanoyl-L-proline-t-butyl ester (0.5 g) was mixed with 4.5 ml of 5.5N methanolic ammonia at room temperature under nitrogen for one hour to remove the acetyl group. The solvent was then removed at 25° C. with a rotary evaporator. After the product was taken up in methanol and re-evaporated twice more in the rotary evaporator, the clear oily residue was dissolved in ethyl ether, washed twice with 5% potassium bisulfate and once with saturated NaCl, dried over MgSO4 and filtered. Residual solvent was removed in vacuo to yield a clear oily product, migrating as a single spot on thin layer chromatography in three separate solvent systems. The t-butyl ester protecting group was removed by reaction with trifluoroacetic acid in anisole.