N-bromobutanimide → Tert-butyl 8-bromo-2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4'-piperidine]-1'-carboxylate

Participants

Reaction Steps

To a solution of tert-butyl 2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (5.60 g, 15.0 mmol) in acetonitrile (50 mL) was added NBS (2.80 g, 15.8 mmol). The mixture was stirred at room temperature overnight. The solvent was removed and the residue was partitioned between EtOAc and water. The aqueous layer was extracted with EtOAc (2×). The combined organic layers were washed with brine, dried over MgSO4 and concentrated to dryness. The crude material was purified by column chromatography (10-20% EtOAc-Hex) to provide tert-butyl 8-bromo-2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (5.40 g, 73%) as a light yellow solid. ESI-MS m/z calc. 452.3. found 454.5 (M+1)+; Retention time: 1.60 minutes (3 minute run).

Provenance & Evidence