The condensation of ethyl indoline-2-carboxylate (I) with N-benzyloxycarbonylalanine (II) by means of CH2Cl2 gives ethyl N-(benzyloxycarbonylalanyl)indoline-2-carboxylate (III), which is hydrolyzed partially with LiOH in DMF water yielding N-(benzyloxycarbonylalanyl)indoline-2-carboxylic acid (IV). Debenzylation of (IV) by hydrogenation with H2 over Pd/C in aqueous ethanol affords N-alanylindoline-2-carboxylic acid, which is finally reductocondensed with ethyl 2-oxo-3-phenylbutyrate (VI) by means of NaOH and sodium cyanoborohydride or H2 and RaNi in ethanol.