O[CH2:2][CH2:3][CH2:4][CH:5]1[CH2:10][CH2:9][CH2:8][CH2:7][N:6]1[C:11]([O:13][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)=[O:12].C(Br)(Br)(Br)[Br:22].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>ClCCl>[Br:22][CH2:2][CH2:3][CH2:4][CH:5]1[CH2:10][CH2:9][CH2:8][CH2:7][N:6]1[C:11]([O:13][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)=[O:12]To a solution of phenylmethyl 2-(3-hydroxypropyl)-1-piperidinecarboxylate (2.14 g, 7.72 mmol) in anhydrous dichloromethane (34 ml) was added carbon tetrabromide (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 10 ml dry DCM was added dropwise over 30 mins., 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 approx 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 cyclohexane over 40 mins. 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).
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