O=[C:2]1[C:6]2=[CH:7][C:8]3[CH:9]=[CH:10][CH:11]=[CH:12][C:13]=3[N:5]2[CH2:4][CH:3]1[C:14]([O:16][CH2:17][CH3:18])=[O:15]>[Ni].C(O)C.O>[CH2:2]1[C:6]2=[CH:7][C:8]3[CH:9]=[CH:10][CH:11]=[CH:12][C:13]=3[N:5]2[CH2:4][CH:3]1[C:14]([O:16][CH2:17][CH3:18])=[O:15]6 spoon spatula measures of Raney nickel were added to a solution of 5.08 g of ethyl 2,3-dihydro-1-oxo-1H-pyrrolo[1,2-a]indole-2-carboxylate in 180 ml of ethanol and 90 ml of water. The mixture was heated to reflux for 10 hours. Then, an additional 3 spoon spatula measures of Raney nickel were added. Heating was continued for 5.5 hours, whereupon the mixture was cooled and filtered. The filter residue was washed with ethyl acetate and dichloromethane. The combined filtrate and washings were evaporated and the residue was purified by chromatography on silica gel with diethyl ether/petroleum ether (1:2). Crystallization from methanol gave 635 mg of ethyl 2,3-dihydro-1H-pyrrolo[1,2-a]indole-2-carboxylate of melting point 55°-57° C.
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