Hydrochloric Acid → 1-methyl-1H-spiro[chromeno[4,3-b]pyrrole-4,4'-piperidine]

Participants

Reaction Conditions

Reaction Steps

A mixture of 2-(1-methylpyrrol-2-yl)phenol (1.20 g, 6.90 mmol), tert-butyl 4-oxopiperidine-1-carboxylate (1.38 g, 6.93 mmol), 4-methylbenzenesulfonic acid hydrate (264 mg, 1.39 mmol), and dichloroethane (24 mL) was heated at 80° C. for 2 h. To the mixture was added HCl (1.7 mL of 4.0 M, 6.9 mmol) and the mixture was allowed to stir at 50° C. for 1 h. The mixture was cooled to 25° C. and was concentrated in vacuo. The residue was taken up in dichloromethane and was washed with saturated aqueous NaHCO3. The organic layer was dried over sodium sulfate and concentrated. Column chromatography (0-100% ethyl acetate/hexanes) on the residue gave 1-methyl-1H-spiro[chromeno[4,3-b]pyrrole-4,4′-piperidine]. ESI-MS m/z calc. 254.3, found 255.2 (M+1)+; Retention time: 1.51 minutes (3 min run).

Provenance & Evidence