Diisobutylaluminumhydride → Tert-butyl 4-fluoro-4-(2-hydroxyethyl)piperidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To tert-butyl 4-(2-ethoxy-2-oxoethyl)-4-fluoropiperidine-1-carboxylate (3.8 g) in DCM (20 ml) at −78° C. under nitrogen was added by syringe diisobutylaluminum hydride (2.2M in Toluene, 24 ml). The mixture was stirred at −78° C. for 2 hours, then warmed up to room temperature. The mixture was then poured to ice (100 g), acidified to pH 3, and extracted with ethyl acetate (200 ml+100 ml×3). Combined ethyl acetate layer was then dried over sodium sulphate, solvent removed to give tert-butyl 4-fluoro-4-(2-hydroxyethyl)piperidine-1-carboxylate which is contaminated with HF eliminated allylic alcohol in ˜3:1 ratio in favour of desired product (3 g). As purification proved to be difficult, this was used for next step as a mixture.

Provenance & Evidence