Ammonia → Tert-butyl 1-oxo-4-phenyl-2,8-diazaspiro[4.6]undecane-8-carboxylate

Participants

Reaction Steps

NaBH4 (570 mg, 15.03 mmol) in EtOH (15 ml) under nitrogen was stirred for 20 minutes and added portionwise (4 aliquots) to a cooled (ice-bath) mixture comprising 1-tert-butyl 4-methyl 4-(2-nitro-1-phenylethyl)azepane-1,4-dicarboxylate (step 2) (1.079 g, 2.504 mmol) and NiCl2 (595 mg, 2.504 mmol) in MeOH (25 ml). After stirring at RT for 1 hour, sat. ammonia solution was added (50 ml) followed by EtOAc (60 ml). The mixture was reduced in vacuo and the resulting slurry was partitioned between sat. ammonia solution and EtOAc. The organic portion was separated and the aqueous was further extracted with EtOAc. The combined organic extracts were washed with brine, dried (MgSO4) and concentrated in vacuo. Purification by chromatography on silica eluting with 1-10% MeOH in TBME afforded the title compound;

Provenance & Evidence