Triphenylphosphine → (2R)-Methyl 2-(tert-butoxycarbonylamino)-(4-((S)-2-methyl-butoxy)-phenyl)acetate

A 0° C. solution of (R)-Methyl 2-(tert-butoxycarbonylamino)-2-(4-hydroxyphenyl)acetate (2.8 g, 10 mmol), (S)-2-methyl-1-butanol (1.1 mL, 10 mmol), triphenylphosphine (2.6 g, 10 mmol), and tetrahydrofuran (100 mL) was treated dropwise with diisopropylazodicarboxylate (1.9 mL, 10 mmol) via syringe. The resulting reaction mixture was allowed to warm to room temperature and maintained overnight. The reaction was concentrated and the residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes) to afford (2R)-Methyl 2-(tert-butoxycarbonylamino)-(4-((S)-2-methyl-butoxy)-phenyl)acetate (2.8 g, 80% yield) as a clear, colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.27 (d, J=7.3 Hz, 2H), 6.88 (d, J=8.6 Hz, 2H), 5.49 (d, J=6.6 Hz, 1H), 5.26 (d, J=7.3 Hz, 1H), 3.81 (dd, J=9.1, 6.1 Hz, 1H), 3.73 (s, 3H), 3.69-3.76 (m, 1H), 1.86 (dq, J=13.1, 6.5 Hz, 1H), 1.52-1.61 (m, 1H), 1.45 (s, 9H), 1.22-1.33 (m, 2H), 1.02 (d, J=6.8 Hz, 3H), 0.95 (t, J=7.5 Hz, 3H); LRMS (ESI) m/e 352.2 [(M+H)+, calcd for C19H30NO5 352.5].

1. customThe resulting reaction mixture
2. temperaturemaintained overnight
3. concentrationThe reaction was concentrated
4. customthe residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes)

ORD record

ord-f8b0fafec7b14b4392a99764911949bc

Source dataset

uspto-grants-2013_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08497271B2