反应详情

A homogeneous mixture containing 2,4,5-trimethoxycinnamaldehyde (7.5 mmol), DDQ (11.3 mmol), MeOH (15 mL) and toluene (10 mL) is taken in a round bottom flask and catalytic amount of AMBERLITE® IR 120 (0.1 g) is added to it. The mixture is refluxed for 6 hrs under Dean Stark apparatus. After completion of the reaction (observed by TLC and by GC analysis), the reaction mixture is filtered and washed with MeOH (5 ml×2). Concentrate the filtrate under reduced pressure and the crude product thus obtained is loaded on a neutral alumina column and eluted with diethyl ether. Methyl 2,4,5-trimethoxycinnamate (from formula I where X1═OCH3, X2═H, X3═OCH3, X4═OCH3, X5═H, R═CH3) is isolated in 84% yield. 1H-NMR (CDCl3, 300 MHz) δ7.91 (1H, d, J=16.10 Hz), 7.01 (1H, s), 6.50 (1H, s), 6.37 (1H, d, J=16.10 Hz), 3.93 (3H, s), 3.88 (3H, s), 3.87 (3H, s), 3.80 (3H, s); 13C-NMR (CDCl3, 75.4 MHz) δ168.2, 153.9, 151.9, 143.4, 139.7, 116.6, 115.4, 112.6, 96.9, 56.5, 56.4, 56.1, 51.5.

1. customis taken in a round bottom flask
2. temperatureThe mixture is refluxed for 6 hrs under Dean Stark apparatus
3. customAfter completion of the reaction (observed by TLC and by GC analysis)
4. filtrationthe reaction mixture is filtered
5. washwashed with MeOH (5 ml×2)
6. concentrationConcentrate the filtrate under reduced pressure
7. customthe crude product thus obtained
8. washeluted with diethyl ether