1-Tert-butyl 3-ethyl piperidine-1,3-dicarboxylate → rac-tert-Butyl 1-oxo-3-phenyl-2,6-diazaspiro[3.5]nonane-6-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of 2M LDA in THF/n-heptane/ethylbenzene (10.7 ml, 21.37 mmol) was cooled to −78° C. and a solution of 1-tert-butyl 3-ethyl piperidine-1,3-dicarboxylate (5 g, 19.43 mmol) in THF (5 mL) was added dropwise. The mixture was stirred for 40 minutes and allowed to warm to 0° C. for 10 minutes and cooled again to −78° C. N-benzylidene-1,1,1-trimethylsilanamine (2.63 ml, 21.37 mmol) was added and the mixture was left to stir for 3 h at 0° C. The reaction was quenched with water (5 ml) and the resulting solution was extracted using ethyl acetate. The organic portion was separated, dried (MgSO4) and concentrated in vacuo to yield a yellow oil. Purification by flash chromatography on silica (220 g column) eluting with 20-70% EtOAc in iso-hexane afforded the title compound;

Provenance & Evidence