Hydrogen Peroxide → Tert-butyl 2-methyl-6,7-bis(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4'-piperidine]-1'-carboxylate

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Reaction Steps

Ferrous sulfate heptahydrate (803 μL of 1.00 M, 0.803 mmol) was added to a mixture of tert-butyl 2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate (1.00 g, 2.68 mmol) and DMSO (15 mL) at room temperature. The vessel was then charged with CF3I (gas) before H2O2 (304 μL of 30% w/v, 2.68 mmol) was added dropwise. The mixture was allowed to stir overnight at room temperature before it was partitioned between ethyl acetate and water. The layers were separated and the aqueous layer was extracted with ethyl acetate (3×). The combined organics were washed with brine, dried over sodium sulfate, filtered and concentrated. The reside was purified by column chromatography (0-100% ethyl acetate/hexanes) to give tert-butyl 2-methyl-6,7-bis(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-carboxylate. ESI-MS m/z calc. 441.2, found 442.5 (M+1)+; Retention time: 1.36 minutes (3 min run).

Provenance & Evidence