1: (2S,3aS,7aS)-phenylmethyl octahydroindole-2-carboxylate hydrochloride; (S)-N-[(S)-1-(ethoxycarbonyl)butyl]alanine With triethylamine in isopropanol acetate T=10 - 15°C; 0.25 h; 2: With 1-propanephosphonic acid cyclic anhydride in isopropanol acetate T=-10 - 30°C; 6 h; 3: tert-butylamine With hydrogen; 5 palladium over charcoal in ethanol