Diisopropylethylamine → Tert-butyl 8-benzyl-9,9-dimethyl-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of tert-butyl 4-[[benzyl-(2-hydroxy-1,1-dimethyl-ethyl)amino]methyl]-4-hydroxy-piperidine-1-carboxylate (330 mg, 0.841 mmol) in tetrahydrofuran was added N,N-diisopropylethylamine (439 μL, 2.52 mmol) and methanesulfonic anhydride (439 mg, 2.52 mmol) under a nitrogen atmosphere. The reaction mixture was heated at 65° C. for 18 h. The reaction mixture was diluted with ethyl acetate, washed with saturated sodium bicarbonate (2×50 mL) and brine (50 mL), dried over Na2SO4, filtered and concentrated in vacuo. The crude material was purified by silica gel chromatography (0-80% of ethyl acetate/hexanes) to provide tert-butyl 8-benzyl-9,9-dimethyl-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (89 mg, 28%) as white solid. ESI-MS m/z calc. 374.5. found 375.3 (M+1)+; Retention time: 1.30 minutes (3 min run).

Provenance & Evidence