(Dimethyl sulfide)trihydroboron → Tert-butyl 7-oxa-3,10-diazaspiro[5.6]dodecane-3-carboxylate

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Reaction Conditions

Reaction Steps

Borane-methyl sulfide complex (2M in THF, 2.88 mL) was added to a solution of tert-butyl 9-oxo-7-oxa-3,10-diazaspiro[5.6]dodecane-3-carboxylate (example 89, step d) (0.41 g) in dry THF (40 mL) and the reaction mixture then heated at 70° C. for 30 minutes under nitrogen. The mixture was cooled to room temperature and quenched with methanol. The solvents were removed under reduced pressure and the residue dissolved in methanol (100 mL). N1,N2-dimethylethane-1,2-diamine (1.0 g) was added and the mixture heated at reflux under nitrogen for 16 h. Further N1,N2-dimethylethane-1,2-diamine (1.0 g) was added and refluxing continued for 16 h. The solvents were evaporated under reduced pressure and the residue azeotroped with toluene. The crude product was purified by flash silica chromatography using 6% methanol in dichloromethane with 1% triethylamine as solvent. Pure fractions were evaporated to dryness to afford the subtitled compound. Yield 0.176 g.

Provenance & Evidence