反应详情

The product of step A (24.5 g, 0.15 mol) was dissolved in acetonitrile/water (1:1, 500 mL) and treated with glyoxylic acid monohydrate (15.3 g, 0.17 mol). The resulting solution was allowed to stir at ambient temperature for 12 h. The reaction mixture was concentrated in vacuo, made basic via addition of 1 M NaOH (500 mL) and extracted with dichloromethane (3×200 mL). The combined organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo to afford crude 1-benzyl-4-hydroxypiperidine-2-carboxylic acid (24 g, 69%) as a colorless oil which was used without further purification: 1H NMR (CDCl3, 400 MHz) δ 7.38-7.27 (m, 5H), 4.82 (t, J=5.2 Hz, 1H), 3.73-3.59 (m, 2H), 3.30 (d, J=4.8 Hz, 1H), 3.03 (dd, J=12.0, 6.4 Hz, 1H), 2.50-2.43 (m, 1H), 2.29-2.19 (m 1H), 2.08-1.98 (m, 1H), 1.97-1.88 (m, 2H).

1. concentrationThe reaction mixture was concentrated in vacuo
2. additionmade basic via addition of 1 M NaOH (500 mL)
3. extractionextracted with dichloromethane (3×200 mL)
4. dry with materialThe combined organic extracts were dried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo