Triethylamine → rac-(2'R,3'S,4'S,5'R)-6-chloro-4'-(3-chloro-2-fluoro-phenyl)-2'-(2,2-dimethyl-propyl)-2-oxo-1,2-dihydro-spiro[indole-3,3'-pyrrolidine]-5'-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To a solution of [3,3-dimethyl-but-(E)-ylideneamino]-acetic acid tert-butyl ester (3.37 g, 15.8 mmol) prepared in Example 1 and E/Z-6-chloro-3-(3-chloro-2-fluoro-benzylidene)-1,3-dihydro-indol-2-one (4 g, 13 mmol) prepared in Example 2 in dichloromethane (100 mL) were added triethylamine (6.6 mL, 47.4 mmol) and AgF (2 g, 15.8 mmol). The mixture was stirred at room temperature for 18 h. The mixture was concentrated, and the residue was partitioned between ethyl acetate and brine. The organic layer was separated, washed with water, dried over MgSO4, and concentrated. The residue was dissolved into t-butanol (30 mL), and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, Fluka) (7.2 g, 47.4 mmol) was added. The reaction mixture was heated at 120° C. for 2 h. The mixture was then cooled to room temperature and concentrated. The residue was partitioned between ethyl acetate and water. The organic layer was separated, and the aqueous layer was extracted with ethyl acetate. The organic layers were combined, washed with water, brine, dried over MgSO4, and concentrated. The residue was purified by chromatography (EtOAc:hexanes=1:3, 1:2) to give as rac-(2′S,3′R,4′S,5′R)-6-chloro-4′-(3-chloro-2-fluoro-phenyl)-2′-(2,2-dimethyl-propyl)-2-oxo-1,2-dihydro-spiro[indole-3,3′-pyrrolidine]-5′-carboxylic acid tert-butyl ester a white foam (2.7 g, 33%)

Provenance & Evidence