反应详情

3-Acetyl-4-hydroxy-6-methyl-pyran-2-one (5.07 g, 30.15 mmol) and 2,4-dimethoxybenzaldehyde (5.03 g, 30.27 mmol) were combined in a 250 mL round bottom flask. Absolute ethanol (20 mL) and piperidine (0.10 eq, 0.30 mL, 3.0 mmol) were added and the mixture heated to between 80 and 85 ° C. The reaction was monitored by TLC (silica gel, hexane-ethyl acetate (1:1 v/v) and methylene chloride-ethyl acetate-acetone (5:5:1 v/v)) and analytical HPLC. After 20 hours (>95% completion) the reaction mixture was cooled to room temperature to provide 3-[3-(2,4-dimethoxy-phenyl)-acryloyl]-4-hydroxy-6-methyl-pyran-2-one as a bright orange crystalline precipitate. MS M+317. NMR (CDCl3-TMS): d 8.31 (m, 2H), 7.69 (d, 1H, J=9 Hz), 6.54 (d, 1H, J=9 Hz), 6.45 (s, 1H), 5.93 (s, 1H), 3.91 (s, 3H), 3.87 (s, 3H), 2.26 (s, 3H) NMR (DMSO-d6): d 8.11 (s, 2H), 7.62 (d, 1H, J=9 Hz), 6.63 (bs, 2H), 6.23 (s, 1H), 3.87 (s, 3H), 3.82 (s, 3H), 2.28 (s, 3H).

1. temperaturethe mixture heated to between 80 and 85 ° C