合成路线1

[U-14C]-Aniline (I) is converted to [U-14C]phenyldiazonium chloride (II), which is condensed in situ with ethyl 2-(ethoxyalyl)propionate (III) to give [U-14C]phenylhydrazone of ethyl pyruvate (IV). Cyclization of (IV) by polyphosphoric acid in xylene affords ethyl [U-14C-phenyl]indole-2-carboxylic acid (V). Catalytic hydrogenation of compound (V) in the presence of platinum gives ethyl [U-14C-cyclohexyl]-(RS)-perhydroindole-2-carboxylic acid (VI), which is saponified to the corresponding acid (VIII). Compound (VI) can also be prepared by reduction of compound (V) with tin and hydrochloric acid to give compound (VII), and hydrogenation of the latter in the presence of palladium. Compound (VIII) is reesterified to the benzyl ester (IX), which is condensed with N-[(S)-1-carbethoxybutyl]-(S)-alanine (X) in the presence of DCC and 1-hydroxy-1-benzotriazole. The resulting compound (X) is separated fom the mixture of isomers by silica gel column chromatography. Hydrogenolysis of the latter compound gives [U-14C-cyclohexyl]perindopril, which is isolated as the tert-bytylamine salt.