Trifluoroacetic acid → 8-Chloro-2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4'-piperidine]

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Reaction Steps

To a solution of tert-butyl 8-chloro-2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (750 mg, 1.84 mmol) in CH2Cl2 (2 mL) was added a prepared solution of 1:1 trifluoroacetic acid (2.0 mL, 26 mmol) in CH2Cl2 (2 mL). After stirring at room temperature for 2 hours, saturated aqueous sodium bicarbonate solution (75 mL) was slowly added. The mixture was extracted with EtOAc (2×75 mL). The organic layers were combined, dried over sodium sulfate, filtered and concentrated under reduced pressure to provide 8-chloro-2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine] (555 mg, 98%) as a yellow-brown solid. ESI-MS m/z calc. 307.1, found 307.9 (M+1)+; Retention time: 1.12 minutes (3 min run). 1H NMR (400 MHz, CDCl3) δ 9.72 (s, 1H), 9.38 (s, 1H), 6.49 (s, 1H), 3.98 (t, J=5.6 Hz, 2H), 3.36 (d, J=11.6 Hz, 2H), 3.26 (d, J=6.1 Hz, 4H), 2.78 (s, 2H), 2.40 (s, 3H), 2.11 (d, J=14.4 Hz, 2H), 1.69 (s, 2H).

Provenance & Evidence