2,4,6-trimethyl-pyridine; (2S,5S)-2,5-bis[[(2S)-3-(1H-indol-3-yl)-1-(octyloxy)-1-oxopropan-2-ylamino]carbonyl]-1-(pyridin-4-yl)pyrrolidine in chloroform T=-60°C; 24 h; chemoselective reaction;

potassium carbonate T=160°C;

phosphoric acid; benzene 8 h;