(2S)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-3-hydroxypropanoic acid → (S)-2-(4-(trifluoromethyl)phenyl)propan-2-yl 2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-hydroxypropanoate

Participants

Reaction Steps

(S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-3-hydroxypropanoic acid (Compound SP827, Fmoc-Ser-OH) (96.0 g, 292 mmol) was azeotropically distilled with THF (100 ml) eight times. This was dissolved in dehydrated THF (200 ml) under a nitrogen atmosphere, 2-(4-(trifluoromethyl)phenyl)propan-2-yl 2,2,2-trichloroacetimidate (Compound SP853) (67.9 g, 195 mmol) was added and the mixture was stirred at room temperature for 3 hours. The reaction mixture was directly purified by amino silica gel column chromatography (DCM) and concentrated under reduced pressure. The residue was further purified by reverse-phase silica gel column chromatography (10 mM aqueous ammonium acetate solution/methanol=95/5→0/100) to afford (S)-2-(4-(trifluoromethyl)phenyl)propan-2-yl 2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-hydroxypropanoate (Compound SP826, Fmoc-Ser-OPis(4-CF3)) (38%, 38.4g).

Provenance & Evidence