Boc-L-dopa tetrabutylammonium salt → (2r)-2-Acetyloxypropyl (2s)-3-(3,4-dihydroxyphenyl)-2-[(tert-butoxy)carbonylamino]propanoate

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Reaction Steps

A solution of Boc-L-Dopa tetrabutyl ammonium salt (5.6 g, 104.0 mmol) and crude (1R)-2-bromomethylethyl acetate (46) (2.6 g, 11.6 mmol) in 50-mL dimethylacetamide was stirred overnight at 65° C. The reaction mixture was diluted with methyl tert-butyl ether (500 mL), washed with saturated aqueous NaHCO3 (3×250 mL), brined, dried over Na2SO4, and concentrated to an oil. Chromatography eluting with EtOAc/hexane (2:3) gave 1.5 g (36.7% yield) of the title compound (47). 1H NMR (400 MHz, CDCl3): δ 1.23 (d, J=6.8 Hz, 3H), 1.43 (s, 9H), 2.10 (s, 3H), 2.98 (m, 2H), 4.02 (dd, J=7.2, 6.8 Hz, 1H), 4.30 (dd, J=6.8, 2.8 Hz, 1H), 4.54 (m, 1H), 4.97 (d, 1H, NH), 5.10 (m, 1H). MS (ESI) m/z 398.1 (M+H)+ and 396.1 (M−H)−.

Provenance & Evidence