Hydrochloric Acid → (S)-3-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)pentanal

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Reaction Steps

(Methoxymethyl)triphenylphosphonium chloride was dried at 80° C. under vacuum for 3 h. To a solution of the dried (methoxymethyl)triphenylphosphonium chloride (1.96 g, 5.71 mmol) in THF (10 mL) was added 0.5 M KHMDS in toluene (10.2 mL, 5.08 mmol) at −78° C. The color of the solution turned blood red in color. After stirring at 0° C. for 30 min., a solution of (S)-2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-2-oxopiperidin-1-yl)butanal (Example 91, Step C; 564 mg, 1.27 mmol) in THF (10.1 mL) was added at 0° C. dropwise. After being stirred at rt for overnight, the reaction was quenched (sat NH4Cl solution), extracted (2×EtOAc), and washed (sat. aq. NaCl solution). The combined organic layers were dried (Na2SO4) and concentrated under reduced pressure. Purification by chromatography on silica gel (SiO2, 40 g, 15% and 20% EtOAc/Hexanes) provided the vinyl ether (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S,E)-1-methoxypent-1-en-3-yl)-3-methylpiperidin-2-one. To a solution of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S,E)-1-methoxypent-1-en-3-yl)-3-methylpiperidin-2-one prepared above in acetonitrile (7.8 mL) was added 3 N hydrochloric acid (4.4 mL, 13 mmol) and the resulting solution was stirred at rt for 1.5 h. Then, the reaction was extracted (2×EtOAc), and washed (sat. aq. NaCl solution). The combined organic layers were dried (Na2SO4) and concentrated under reduced pressure to provide the title compound as a pale yellow film.

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