Trifluoroacetic acid → (2R)-amino-5-(1,3-dioxo-1,3-dihydroisoindol-2-yl)pentanoic acid t-butyl ester

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Reaction Steps

A solution of the title G compound, (2R)-(t-butyloxycarbonylamino)-5-(1,3-dioxo-1,3-dihydroisoindol-2-yl)pentanoic acid t-butyl ester (4.83 g, 11.55 mmol) in 18 mL of dichloromethane is treated with trifluoroacetic acid (TFA; 6.00 mL, 78 mmol) at 0° C. After stirring for 1 h at this temperature, the solution is concentrated under reduced pressure without heating, and the residue is partitioned between 100 mL of ethyl acetate and 50 mL of 1M aqueous NaHCO3. The organic phase is dried over anhydrous Na2SO4 and concentrated. Chomatography on silica gel (eluant; 1/1—ethyl acetate/hexane) affords 2.58 g (70%) of (2R)-amino-5-(1,3-dioxo-1,3-dihydroisoindol-2-yl)pentanoic acid t-butyl ester as a colorless foam: NMR(CDCl3) 1.46 (s, 9H), 1.80-2.06 (m, 4H), 3.73 (t, 2H, J=6.2), 3.97 (t, 1H, J=6.3), 7.68-7.71 (m, 2H), 7.82-7.85 (m, 2H).

Provenance & Evidence