A mixture comprising 2-isopropyl-4-phenyl-2,7-diazaspiro[4.5]decan-1-one (ASW MedChem) (278 mg, 0.899 mmol), (R)-2-(2-(tert-butoxycarbonylamino)-2-methylpropanamido)-3-(1H-indol-3-yl)propanoic acid (Intermediate 3C) (350 mg, 0.899 mmol) and DIPEA (0.628 ml, 3.59 mmol) in DMF (4 ml) was treated with ®T3P (50% in DMF, 0.525 ml, 1.797 mmol) and stirred at RT for 2 h 20 min. The reaction mixture was diluted with water (5 ml) and extracted with EtOAc. The organic portion was dried (MgSO4) and concentrated in vacuo Purification of the crude product by chromatography on silica eluting with 1% MeOH in DCM afforded the title compound;
