反应详情

To a solution of potassium t-butoxide (0.673 g) in THF (20 mL) under nitrogen and cooled in an ice bath was added a solution of 1-(1-benzylpiperidin-4-yl)-4-phenylbutan-1-one from Step D (0.71 g) and methyl formate (3.76 mL) in THF (12 mL) over 5 minute. The reaction was stirred for 15 min before being allowed to warm to rt for 2 h. The reaction was poured into water and extracted with ether (4×100 mL), methylene chloride (100 mL), and THF (100 mL). The combined organic layers were washed with water and brine, dried over sodium sulfate and concentrate under reduced pressure. The crude product was purified by FC on silica gel eluting with 5 and 20% methanol in ethyl acetate with 4% TEA to afford the title compound (0.8 g). 1H NMR (500 MHz, CDCl3) showed a 3:1 ratio of enol (δ8.54 ppm) and aldehyde (δ9.54 ppm) forms. Other signals from the two forms were only partially resolved. The title compound had a retention time of 9.47 min on a Zorbax SB-C18 column (4.6×75 mm) eluting with 20-100% gradient of acetonitrile in water with 0.1% TFA over 10 min at 1 mL per min.

1. extractionextracted with ether (4×100 mL), methylene chloride (100 mL), and THF (100 mL)
2. washThe combined organic layers were washed with water and brine
3. dry with materialdried over sodium sulfate
4. concentrationconcentrate under reduced pressure
5. customThe crude product was purified by FC on silica gel eluting with 5 and 20% methanol in ethyl acetate with 4% TEA