反应详情

A solution of compound (2a) (11.07 g, 55.2 mmol), malonic acid (8.639 g, 83 mmol) and piperidine (2 ml, 1.722 g, 20.2 mmol) in 80 ml of anhydrous pyridine was refluxed (bath temperature 110° C.) for 2 h. Reaction mixture was cooled, concentrated under vacuum and acidified 250 ml of 5% aqueous citric acid to a pH of 3. Resulted heterogeneous mixture was sonicated for a few minutes. The precipitated material was filtered off, washed with water (2×20 ml) and dried in vacuum over KOH to give 12.7 g (52.3 mmol, 95% yield) of pure (HPLC, 1H NMR) desired acid 3a as a white solid. 1H NMR (DMSO-d6): δ 7.77 (d, J=9.0 Hz, 1H), 7.67 (d, J=16.0 Hz, 1H), 7.01 (d, J=9.0 Hz, 1H), 6.51 (d, J=16.0 Hz, 1H), 3.90 (s, 3H), 3.77 (s, 3H).

1. customReaction mixture
2. temperaturewas cooled
3. concentrationconcentrated under vacuum
4. customResulted heterogeneous mixture
5. customwas sonicated for a few minutes
6. filtrationThe precipitated material was filtered off
7. washwashed with water (2×20 ml)
8. dry with materialdried in vacuum over KOH