Ethanol → HCID 58815870, compound

Participants

Reaction Steps

The ketal of the preceding product, Example 135, was hydrolyzed as follows. A 500 mL round bottom flask equipped with a magnetic stir bar was charged with 21.40 g (40.9 mmol) of {3-[(R)-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)(3-hydroxy-phenyl)methyl]phenyl}-(1,4-dioxa-8-azaspiro[4.5]dec-8-yl)methanone, 180 mL ethanol, and 60 mL 10 N aqueous sulfuric acid. The reaction was stirred at room temperature for 20 hours and concentrated under reduced pressure. The residue was partitioned between 150 mL dichloromethane and water, and the aqueous solution was adjusted to pH=8-9 using 50% aqueous NaOH. The layers were separated and the aqueous phase was washed with dichloromethane (2×30 mL). The combined organic extracts were dried over sodium sulfate/magnesium sulfate and the solvent was removed in vacuo, leaving 20.25 g of crude product as a light yellow, viscous oil. Chromatography of this material on ˜100 g of silica gel eluting with dichloromethane/ethyl acetate with 2% ammonium hydroxide yielded 15.30 g (81%) of 1-{3-[(R)-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)(3-hydroxyphenyl)-methyl]-benzoyl}-4-piperidinone as an off-white solid. This material contained 12-13% (as estimated by NMR) of the starting ketal, and was difficult to purify further without significant loss of material. 1H NMR (300 MHz, CDCl3): {tilde over (□)}□{tilde over ()}d, J=6.9 Hz, 1H), 7.45 (s, 1H), 7.40-7.32 (m, 2H), 7.10 (t, J=7.8 Hz, 1H), 6.61 (t, J=7.8 Hz, 2H), 6.56 (s, 1H), 5.94-5.81 (m, 1H), 5.21 (d, J=7.8 Hz, 2H), 5.17 (s, 1H), 3.8 (v br s, 4H), 3.42 (dd, J=5.1, 13.5 Hz, 1H), 2.89-2.82 (m, 2H), 2.62-2.38 (m, 7H), 2.13 (dd, J=1, 10 Hz, 1H), 1.93 (dd, J=1, 9.5 Hz, 1H), 1.17 (d, J=5.9 Hz, 3H), 1.00 (d, J=6.1 Hz, 3H).

Provenance & Evidence