Trifluoroacetic acid → 10-Phenyl-8-(2,2,2-trifluoroethyl)-11-oxa-3,8-diazaspiro[5.5]undecane

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Reaction Steps

To tert-butyl 10-phenyl-8-(2,2,2-trifluoroethyl)-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (779 mg, 1.86 mmol) in dichloromethane (5 mL) was added 2,2,2-trifluoroacetic acid (5 mL, 64.90 mmol) at room temperature. The reaction mixture was stirred for 40 minutes, then diluted with dichloromethane (75 mL) and the organic solution was washed with saturated sodium bicarbonate (twice) and then brine. The organic layer was dried over sodium sulfate, filtered and the solvent was removed in vacuo to give 10-phenyl-8-(2,2,2-trifluoroethyl)-11-oxa-3,8-diazaspiro[5.5]undecane as an amber oil (585 mg, 99%). ESI-MS m/z calc. 314.2. found 315.3 (M+1)+; Retention time: 1.29 minutes (3 min run). 1H NMR (400 MHz, CD3CN) δ 7.44-7.25 (m, 5H), 4.82 (dd, J=10.6, 2.8 Hz, 1H), 3.74 (br s, 1H), 3.06 (q, J=9.8 Hz, 2H), 3.02-2.91 (m, 2H), 2.88 (dd, J=11.2, 1.5 Hz, 1H), 2.85-2.74 (m, 3H), 2.34 (d, J=14.8 Hz, 1H), 2.28 (dt, J=10.9, 5.3 Hz, 2H), 1.76-1.64 (m, J=16.0, 8.7, 5.3 Hz, 1H), 1.64-1.52 (m, 2H).

Provenance & Evidence