Carbon tetrabromide → Benzyl 2-(3-bromopropyl)piperidine-1-carboxylate

Participants

Reaction Steps

To a solution of phenylmethyl 2-(3-hydroxypropyl)-1-piperidinecarboxylate (for example, as prepared for Intermediate 9) (2.14 g, 7.72 mmol) in anhydrous dichloromethane (34 mL) was added carbon tetrabromide (commercially available, for example, from Aldrich) (5.12 g, 15.43 mmol). The resulting solution was cooled in ice/water. A solution of triphenylphosphine (4.05 g, 15.43 mmol) in dry DCM (10 mL) was added dropwise over 30 minutes, producing a deep amber/brown solution. After complete addition, the reaction was allowed to warm slowly to ambient temperature and stirring continued overnight. The reaction mixture was filtered to remove the precipitate, washed with ether and the filtrate evaporated to ˜10 mL. This was then loaded onto a 100 g silica cartridge and purified by chromatography using a gradient of Flashmaster 0-25% ethylacetate in cylcohexane over 40 minutes on a Flashmaster collecting all the eluent. The product peak was identified by TLC and the fractions combined and evaporated in vacuo to give the title compound as a clear oil (2.13 g)

Provenance & Evidence