Diisopropylethylamine → (S)-ethyl 1-((S)-2-(tert-butoxycarbonylamino)-3-methylbutanoyl)indoline-2-carboxylate

N,N,N′,N′-tetramethylfluoroformamidinium hexafluorophosphate (1.1 g, 4.18 mmol, Eq: 1.6) was added to a solution of (S)-2-(tert-butoxycarbonylamino)-3-methylbutanoic acid (738 mg, 3.4 mmol, Eq: 1.3) and diisopropylethylamine (1.4 mL, 7.84 mmol, Eq: 3) in DCM (10 mL) and the resulting solution was stirred at rt for 1 h. (S)-Ethyl indoline-2-carboxylate (0.5 g, 2.61 mmol, Eq: 1.00) was added and the reaction mixture was stirred at rt over the weekend. The reaction mixture was diluted with EtOAc (50 mL) and washed with 0.1 M aqueous HCl (50 mL), 0.1 M aqueous NaOH (50 mL) and brine (25 mL). The crude material was purified by flash chromatography (silica gel, 24 g, 0% to 20% EtOAc in hexanes) to give (S)-ethyl 1-((S)-2-(tert-butoxycarbonylamino)-3-methylbutanoyl)indoline-2-carboxylate (0.58 g), m/z=391 (M+H).

1. additionwas added
2. washwashed with 0.1 M aqueous HCl (50 mL), 0.1 M aqueous NaOH (50 mL) and brine (25 mL)
3. customThe crude material was purified by flash chromatography (silica gel, 24 g, 0% to 20% EtOAc in hexanes)

ORD-Eintrag

ord-4be0ba8db82c4ca68a42af5c478c5ed1

Quelldatensatz

uspto-grants-2016_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09403768B2