Hydrochloric Acid → (+/-)-2'-Oxo-1',2',6,8-tetrahydrospiro[cyclopenta[g]quinoline-7,3'-pyrrolo[2,3-b]pyridine]-3-carbaldehyde

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Reaction Steps

(±)-5-Amino-1,3-dihydrospiro[indene-2,3′-pyrrolo[2,3-b]pyridin]-2′(1′H)-one (125 mg, 0.500 mmol, described in Intermediate 4) and 2-dimethylaminomethylene-1,3-bis(dimethylimmonio)propane bis(tetrafluoroborate) (266 mg, 0.750 mmol) were suspended in glacial acetic acid and the mixture was heated to reflux for 22 h. The mixture was allowed to cool to ambient temperature before the bulk of the acetic acid was removed in vacuo. THF (3 mL) and 1 N HCl (3 mL, 3 mmol) were added and the mixture was stirred at ambient temperature for 2 h. The mixture was then poured into a separatory funnel containing CHCl3 (50 mL) and saturated aqueous NaHCO3 (10 mL). The aqueous layer was extracted twice with CHCl3 (2×250 mL) and the combined organic layers were dried over Na2SO4. Filtration to remove drying agent gave a solution which was concentrated in vacuo to give a yellow residue. The impure product was purified by silica gel chromatography, eluting with a gradient of CH2Cl2:MeOH—100:1 to 92:8, to give the title compound. MS: m/z=316 (M+1).

Provenance & Evidence