[Cl:1][C:2]1[CH:10]=[C:9]2[C:5]([CH2:6][CH2:7][C:8]2=[O:11])=[CH:4][C:3]=1[O:12][CH3:13].C[Si]([N-][Si](C)(C)C)(C)C.[Li+].C([C:26]([O:28][CH2:29][CH3:30])=[O:27])#N>C1COCC1>[Cl:1][C:2]1[CH:10]=[C:9]2[C:5]([CH2:6][CH:7]([C:26]([O:28][CH2:29][CH3:30])=[O:27])[C:8]2=[O:11])=[CH:4][C:3]=1[O:12][CH3:13]To a solution of 6-chloro-5-methoxyindan-1-one (27.6 g, 141 mmol) in THF (630 mL) at −78° C. was added a 1.0M solution of lithium bis(trimethylsilyl)amide in THF (309 mL, 309 mmol) and then the solution was slowly warmed to ca −50° C. during 1 hour. After re -cooling to −78° C., ethyl cyanoformate (21.3 mL, 216 mmol) was introduced and the reaction mixture was allowed to warm to room temperature during 2 hours. After quenching with 300 mL of 1N HCl, most of the THF was removed by rotary evaporation under reduced pressure. The residual mixture was extracted with EtOAc and the organic layer was washed with dilute aqueous NaHCO3 and dried over Na2SO4. Filtration through a pad of silica and removal of the solvent under reduced pressure gave ethyl 6-chloro-5-methoxy-1-oxoindane-2-carboxylate as a brown oil.
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