合成路线1

N-Protection of L-Dopa (I) by means of Boc2O and Et3N in H2O-dioxane yields Boc derivative (II), which is then benzylated by reaction with benzyl bromide (III) and K2CO3 in refluxing acetone to provide (IV). Benzyl ester moiety of (IV) is saponified by treatment with NaOH in H2O-dioxane to give carboxylic acid (V), and deprotection of the amino group by means of TFA in CH2Cl2 furnishes trifluoroacetate salt (VI). Acylation of the amine group of (VI) with chloroacetyl chloride (VII) in NaOH yields N-chloroacetyl derivative (VIII), which is cyclized by heating in DMF in the presence of Et3N to afford morpholinedione (IX). Hydrogenation of (IX) over Pd/C in HCl/EtOH provides debenzylated derivative (X), which is finally converted into the desired compound by selective acylation with pivaloyl chloride (XI) in TFA.