Trifluoromethanesulfonyl chloride → Tert-butyl 6-chloro-2-methyl-spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4'-piperidine]-1'-carboxylate

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Reaction Steps

To tert-butyl 2-methylspiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (5 g, 16.37 mmol) in dichloromethane (50.00 mL) at 0° C. was added trifluoromethanesulfonyl chloride (3.64 mL, 34.38 mmol) and the reaction was stirred from 0° C. to room temperature overnight. The reaction was diluted with dichloromethane and washed with water. The layers were separated and the organics were dried over sodium sulfate, filtered and concentrated. Purification of the residue by silica gel chromatography eluting with 10-100% ethylacetate in hexanes afforded tert-butyl 6-chloro-2-methyl-spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (4.3 g, 77%), as a yellow solid. ESI-MS m/z calc. 339.2, found 340.3 (M+1)+; Retention time: 1.13 minutes (3 min run). 1H NMR (400 MHz, CDCl3) δ 6.01 (d, J=3.8 Hz, 1H), 5.91 (d, J=3.7 Hz, 1H), 3.77 (t, J=6.1 Hz, 2H), 3.34 (s, 2H), 3.24 (s, 2H), 2.34 (s, 3H), 2.03 (d, J=13.1 Hz, 2H), 1.74 (t, J=11.1 Hz, 2H), 1.47 (s, 9H).

Provenance & Evidence