Hydrochloric Acid → (5S,8R)-5-benzyl-1-(9H-fluoren-9-yl)-12,12-dimethyl-3,6-dioxo-2-oxa-10,11-dithia-4,7-diazatridecane-8-carboxylic acid

Participants

Reaction Steps

A solution of Fmoc-Phe-OH (4 g, 10.32 mmol) and N-hydroxysuccinimide (1.19 g, 10.32 mmol) in dichloromethane (20 ml) was cooled to 0° C., after which 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl, 1.98 g, 10.32 mmol) was added and the reaction solution was stirred at room temperature for 6 hours. The reaction solution was cooled to 0° C., after which N,N-diisopropylethylamine (1.80 ml, 10.23 mmol) and S-(t-butylthio)-L-cysteine (H-Cys(StBu)-OH) (2.16 g, 10.32 mmol) were added and the reaction solution was stirred at room temperature for 12 hours. Ethyl acetate and 2 M hydrochloric acid were added to the reaction mixture, followed by extraction with ethyl acetate. The organic layer was washed with 25 wt % brine and dried over sodium sulfate. The resulting solution was concentrated under reduced pressure, and the concentration residue was purified by reverse-phase silica gel column chromatography (0.1% aqueous formic acid solution/0.1% formic acid-acetonitrile solution) to afford (5S,8R)-5-benzyl-1-(9H-fluoren-9-yl)-12,12-dimethyl-3,6-dioxo-2-oxa-10,11-dithia-4,7-diazatridecane-8-carboxylic acid (Compound SP663, Fmoc-Phe-Cys(StBu)-OH) (4.22 g, 71%).

Provenance & Evidence