Allyl bromide → (5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one

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Reaction Conditions

Reaction Steps

A solution of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(2,4-dimethoxybenzyl)-3-methylpiperidin-2-one (Example 71, Step B, mixture of C-3 diastereomers) (117.0 g, 242 mmol) in anhydrous THF (966 mL) was degassed by bubbling argon through the solution for 20 minutes. Allyl bromide (105 mL, 1208 mmol) was added followed by the addition of LHMDS (725 mL, 725 mmol) over 20 minutes. The reaction mixture was heated at 40° C. under argon for 5 hours. The reaction mixture was cooled to rt. and the reaction was quenched by the addition of sat. aqueous NH4Cl (500 mL) and the layers were separated. The aqueous layer was extracted with EtOAc (2×1 L) and the organics were pooled, washed with sat. aq. NaCl solution (1 L), dried (MgSO4), filtered and concentrated in vacuo to provide a red oil (180 g). Purification using the Biotage system (Charlotte, N.C.) with a 1.5 kg SiO2 column and eluting with 10-30% EtOAc/hexanes provided the title compound as a very pale yellow oil as a 3.7:1 mixture of (3S):(3R) diastereomers.

Provenance & Evidence