Tert-butoxycarbonylalanine → 2,2-Dimethylpropionic acid 2-{(S)-3-[2-((S)-2-tert-butoxycarbonylaminopropionylamino)-5-fluorophenylamino]piperidin-1-yl}ethyl ester

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Reaction Steps

To an ice-cooled mixture of 2,2-dimethylpropionic acid 2-[(S)-3-(2-amino-5-fluorophenylamino)piperidin-1-yl]ethyl ester (1.464 g, 4.34 mmol), (S)-2-tert-butoxycarbonylaminopropionic acid (0.904 g, 4.77 mmol) and HOAt (0.591 g, 4.34 mmol) in DCM (40 mL) was added N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (1.0 g, 5.21 mmol) portion wise over 10 min. The reaction mixture was stirred in the ice bath for 2 h, then diluted with DCM, washed with 2M Na2CO3 then water. The organic fractions were dried (Na2SO4) then concentrated in vacuo. The resulting residue was purified by column chromatography (Si—PCC, gradient 40-70% EtOAc in cyclohexane) affording the title compound as a dark red gum (2.054 g, 93%). LCMS (Method B): RT 2.46 min [M+H]+ 509.

Provenance & Evidence