Patent ID: 9533941
Date: 2017-01-03
CPC Classifications: A61P,C07C

Claim:
1. A method of synthesizing (2R)-2-phenylcarbonyloxypropyl (2S)-2-amino-3-(3,4-dihydroxyphenyl)propanoate salt comprising: reacting (2S)-2-amino-3-(3,4-dihydroxyphenyl)propanoic acid with di-tert-butyl dicarbonate and tetrabutylammonium hydroxide in a mixture of alcohol and from 0%-b.v. to 4 b.v. water at a temperature from 20° C. to 60° C. in an inert atmosphere, to provide 3-(3,4-dihydroxyphenyl)-(2S)-[(tert-butoxy)carbonylamino]propanoate tetrabutylammonium salt; and reacting the 3-(3,4-dihydroxyphenyl)-(2S)-[(tert-butoxy)carbonylamino]propanoate tetrabutylammonium salt with (1R)-2-chloro-isopropyl benzoate in N-methyl-2-pyrrolidone at a temperature from 50° C. to 120° C. to provide (2R)-2-phenylcarbonyloxypropyl(2S)-3-(3,4-dihydroxyphenyl)-2-[(tert-butoxy)carbonylamino] propanoate.