The protection of the amino group of L-(2-naphthyl)alanine (I) with di-tert-butyl dicarbonate and triethylamine gives N-tert-butoxycarbonyl-L-(2-naphthyl)alanine (II), which is amidated with benzylmethylamine by means of hydroxybenzotriazole (HOBT) and 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (WSC) in dichloromethane yielding N-tert-butoxycarbonyl-L-(2-naphthyl)alanine N-benzyl-N-methylamide (III). Elimination of the tert-butoxycarbonyl group of (III) with HCl in dioxane affords L-(2-naphthyl)alanine N-benzyl-N-methylamide (IV), which is condensed with N-(tert-butoxycarbonyl)-[4(R)-hydroxy]-L-proline (V) by means of HOBT an WSC as before giving the protected dipeptide (VI). Elimination of the protecting group of (VI) with HCl in dioxane as before yields the dipeptide (VII) with the free amino group, which is finally acylated with 1-methylindole-3-carboxylic acid (VIII) by means of HOBT and WSC as before.