Water → HCID 178523874, compound

Participants

Reaction Steps

Aqueous sodium hydroxide (15.4 g, 192 mL, 0.08 g/mL solution, 0.38 mol) was added to a solution of dipeptide 25 (187.1 g, ca. 0.38 mol), water (360 mL) and MeOH (ca. 6 L). The solution was stirred at room temperature until hydrolysis was complete (ca. 24 hours). The disappearance of the starting peptide was established by HPLC analysis. The solution was concentrated in vacuo to a residue which was dissolved in water (ca. 1 L). The aqueous layer (pH ca. 10) was then extracted with EtOAc (2×500 mL) in a separatory funnel. The resulting aqueous phase was adjusted to a pH of 5 with concentrated HCl at which point a crystalline precipitate formed. The solid was collected by vacuum filtration and dried in vacuo (148.4 g, 0.31 mol, 82%). The pH of the filtrate was adjusted to 4.5. A second crop of solid was again collected by vacuum filtration and dried in vacuo (20.2 g, 0.043 mol, 11%). 1H NMR showed both samples to contain dipeptide 26 in high purity. In two repetitions of this reaction, yields of 83% (ca. 0.06 mole scale) and 58% (ca. 0.3 mole scale) were obtained.

Provenance & Evidence