[C:1]1(=O)[CH2:6][CH2:5][CH2:4][CH2:3][CH2:2]1.[NH:8]1[C:16]2[C:11](=[CH:12][CH:13]=[C:14]([C:17]([O:19][CH3:20])=[O:18])[CH:15]=2)[CH:10]=[CH:9]1.FC(F)(F)C(O)=O.C([SiH](CC)CC)C>ClCCl>[CH:1]1([C:10]2[C:11]3[C:16](=[CH:15][C:14]([C:17]([O:19][CH3:20])=[O:18])=[CH:13][CH:12]=3)[NH:8][CH:9]=2)[CH2:6][CH2:5][CH2:4][CH2:3][CH2:2]1
Cyclohexanone (42.46 mL, 0.40 mol) was added in a single portion to a stirred solution of methyl indole-6-carboxylate (47.8 g, 0.27 m) in dry dichloromethane (500 mL). The reaction mixture was then cooled to 10° C. and trifluoroacetic acid (63.13 mL, 0.8 m) was added dropwise followed by triethyl silane (174.5 mL, 1.09 m). Upon addition, the temperature was allowed to rise to rt, after which it was stirred for a further 12 h. Dichloromethane (200 mL) was then added and the reaction mixture was washed successively with with 10% sodium bicarbonate solution and brine. The organic layer dried over sodium sulfate, filtered and concentrated under vacuum. The resultant residuce was purified by flash chromatography on silica (60-120) using hexane-ethyl acetate (9.5:0.5) mixture as eluant. Homogeneous fractions were combined and evaporated to give 60 g of the desired product (85%). Analytical data on this material was consistant with that observed with a sample prepared by the alternative route described above.
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