Butanoic acid, 4-chloro-4-oxo-, ethyl ester → HCID 57426203, compound

Reaction equation

[N+:1]([C:4]1[CH:12]=[CH:11][CH:10]=[C:9]2[C:5]=1[CH:6]=[CH:7][NH:8]2)([O-:3])=[O:2].[Cl-].C[Al+]C.Cl[C:18](=[O:26])[CH2:19][CH2:20][C:21]([O:23][CH2:24][CH3:25])=[O:22]>C(Cl)Cl>[N+:1]([C:4]1[CH:12]=[CH:11][CH:10]=[C:9]2[C:5]=1[C:6]([C:18](=[O:26])[CH2:19][CH2:20][C:21]([O:23][CH2:24][CH3:25])=[O:22])=[CH:7][NH:8]2)([O-:3])=[O:2]

Participants

Procedure

To a stirred solution of 4-nitroindole (2.00 g, 12.3 mmol) in CH2Cl2 (60 mL) at 0° C. was added dimethylaluminum chloride (1 M in hexanes, 14.8 mL, 14.8 mmol) and the mixture was stirred for 30 min. Ethyl 4-chloro-4-oxobutyrate (2.44 g, 14.8 mmol) was added dropwise and the resulting mixture was allowed to warm slowly to ambient temperature and stirred for 18 h. The reaction mixture was carefully quenched with 10% aqueous citric acid (150 mL) and extracted with CH2Cl2 (3×150 mL). The combined organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo. The residue was partially purified by silica gel chromatography, eluting with a gradient of CH2Cl2:EtOAc—100:0 to 65:35, and the resulting crude product was recrystallized from CH2Cl2:MeOH to give the title compound. MS: m/z=291 (M+1).