Tetrahydrofuran → Tert-butyl 8-but-2-ynyl-10,10-difluoro-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

Borane dimethylsulfide (36.3 μL, 0.408 mmol) was added dropwise to a solution of tert-butyl 10,10-difluoro-9-oxo-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate (125 mg, 0.408 mmol) in tetrahydrofuran (3 mL). The reaction mixture was heated at 55° C. for 2 h then cooled to room temperature. The mixture was quenched with the careful dropwise addition of methanol (˜2 mL). N,N-dimethylethane-1,2-diamine (33.3 μL, 0.313 mmol) was then added and the mixture heated at 70° C. for 40 min. The reaction was concentrated, and silica gel chromatography (4 g silica, 1% triethylamine/4% methanol/dichloromethane)) provided tert-butyl 8-but-2-ynyl-10,10-difluoro-11-oxa-3,8-diazaspiro[5.5]undecane-3-carboxylate which was taken directly to the next reaction.

Provenance & Evidence