Sodium Bicarbonate → Tert-butyl 8-(2,2-difluoroethyl)-10-(2-pyridyl)-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate

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To tert-butyl 10-(2-pyridyl)-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (63 mg, 0.19 mmol) in ethanol was added sodium hydrogen carbonate (64 mg, 0.76 mmol) followed by the addition of 2,2-difluoroethyl trifluoromethanesulfonate (49 mg, 0.23 mmol) and reaction mixture was heated at 80° C. for 40 minutes. The reaction mixture was cooled to room temperature and diluted with DCM and the organic layer was washed with 1:1 NaOH:NaHCO3 solution. The organics were separated, dried over Na2SO4, filtered and concentrated in vacuo to give tert-butyl 8-(2,2-difluoroethyl)-10-(2-pyridyl)-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate as an oil. To the oil was added HCl (237.5 μL of 4 M in dioxane, 0.95 mmol) at room temperature under an atmosphere of nitrogen and the reaction mixture was stirred for 30 minutes. The solvent was removed in vacuo and the residue was triturated with ether to give 8-(2,2-difluoroethyl)-10-(2-pyridyl)-11-oxa-3,8-diazaspiro[5.5]undecane (45 mg, 79%). ESI-MS m/z calc. 297.3. Found 298.4 (M+1)+; Retention time: 0.35 minutes (3 min run).

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