Trifluoromethanesulfonic acid → Ethyl 1-[(4-nitrophenyl)sulfonyl]-8-oxa-1-azaspiro[4.5]decane-2-carboxylate

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Reaction Steps

To a solution of ethyl 2-{[(4-nitrophenyl)sulfonyl]amino}-4-(tetrahydro-4H-pyran-4-ylidene)butanoate (164) (1.87 g, 4.7 mmol) in anhydrous chloroform (47 mL) was added trifluoromethanesulfonic acid (0.2 mL, 2.3 mmol) and the reaction stirred at room temperature under nitrogen for 4 h. The reaction was diluted with dichloromethane and washed with saturated NaHCO3 and the organic layer dried over MgSO4 and concentrated in vacuo. The residue was purified by silica gel chromatography eluting with 10-70% hexanes/EtOAc to afford the title compound as a white solid (1.47 g, 79% yield). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 8.19-8.36 (m, 2H) 8.08 (d, J=8.8 Hz, 2H) 4.52 (dd, J=8.5, 2.1 Hz, 1H) 3.99-4.14 (m, 2 H) 3.87-3.99 (m, 2H) 3.21-3.49 (m, 2H) 2.58-2.78 (m, 2H) 2.10-2.30 (m, 2H) 1.89-2.06 (m, 2H) 1.77 (dd, J=13.0, 2.1 Hz, 1H) 1.35 (dd, J=12.9, 1.6 Hz, 1H) 1.22 (t, J=7.1 Hz, 3H). LC-MS ESI (M+H)+=399.47.

Provenance & Evidence