合成路线1

6) The cyclization of L-4-nitrophenylalanine (I) with benzyl isocyanate (XIII) in hot water gives (S)-5-(4-nitrobenzyl)imidazolidine-2,4-dione (XIV), which is reduced with H2 over Pd/C in ethanol/water to the corresponding amino derivative (XV). The diazotation of (XV) with NaNO2.HCl, followed by reduction with SnCl2 in water affords the expected hydrazino derivative (XVI), which is cyclized with 4-chlorobutanal diethylacetal (VII) in refluxing ethanol/water to give (S)-5-[3-(2-aminoethyl)-1H-indol-5-ylmethyl]imidazolidine-2,4-dione (XVII). The reductive methylation of (XVII) with formaldehyde and sodium cyanoborohydride yields (S)-5-[3-[2-(dimethylamino)ethyl]-1H-indol-3-yl]alanine (XIX). The esterification of (XIX) with SOCl2 and methanol affords the corresponding methyl ester (XX), which is reduced with NaBH4 in ethanol/water giving the 2(S)-aminopropanol derivative (XXI). Finally, this compound is cyclized with diethyl carbonate and potassium carbonate at 130 C. 7) The cyclization of hydrazino derivative (XVI) with 4-(dimethylamino)butanal diethylacetal (IX) in refluxing acetic acid/water directly yields (S)-5-[3-[2-(dimethylamino)ethyl]-1H-indol-5-ylmethyl]imidazolidine-2,4-dione (XVIII), already reported.