Hydrochloric Acid → (S)-2-((S)-2-amino-3-(1H-indol-3-yl)propanamido)-3-(tert-butyldisulfanyl)propanoic acid

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Reaction Steps

A solution of ((S)-2-((S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(1H-indol-3-yl)propanamido)-3-(tert-butyldisulfanyl)propanoic acid (Fmoc-Trp-D-Cys(StBu)-OH) (Compound SP642) (1.93 g, 3.12 mmol) in N,N-dimethylformamide (6.3 mL) was mixed with 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) (706 μL, 4.69 mmol) with stirring at room temperature, and the reaction solution was stirred at room temperature for 1 hour. 1 N hydrochloric acid was added to the reaction solution, and the organic layer was extracted with ethyl acetate, washed with brine and then dried over sodium sulfate. Following concentration under reduced pressure, the resulting residue was purified by reverse-phase silica gel column chromatography (0.1% aqueous formic acid solution/0.1% formic acid-acetonitrile solution) to afford (S)-2-((S)-2-amino-3-(1H-indol-3-yl)propanamido)-3-(tert-butyldisulfanyl)propanoic acid (H-Trp-D-Cys(StBu)-OH) (Compound SP643) (870 mg, 2.20 mmol, 70%).

Provenance & Evidence