Piperonal → (e)-1-(3,4-Methylenedioxyphenyl)-3-(3,5-dimethoxyphenyl)prop-1-en-3-one

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Reaction Steps

To a stirred solution of Piperonal (1.00 g, 6.67 mmol) and 3,5-dimethoxyacetophenone (1.20 g, 6.67 mmol) in methanol (30 ml) was added a 50% w/v solution of aqueous NaOH (8 ml, 15 eq). A colourless solution had formed initially following the dissolution of the two starting materials in the solvent, but upon addition of NaOH, the solution became a yellow, creamy suspension. A pale yellow precipitate was noticed approximately 2 or 3 mins after adding the aqueous NaOH. A further 3 ml (˜5 eq) of base was added, after 5 h, in order to drive the reaction to completion. The mixture was stirred for a total of 6 h at room temperature. The precipitate was collected via vacuum filtration and the filtrate discarded. The solid was purified by recrystallisation from hot methanol and hot filtration. The product was collected and allowed to be dried under vacuum to afford the title compound as a pale yellow solid (0.53 g, 25%). 1H-NMR (CDCl3) δ 7.25 (1H, d, CH(9)), 7.30(2H, d, CH(6&8)), 6.85 (1H, d, CH(3)), 6.65 (1H, t, CH(4)), 6.00 (2H, s, CH2(1)), 3.85 (6H, s, OCH3(5&7)); 13C-NMR (CDCl3) δ 189.958 (C═O), 160.870, 149.928, 148.401, 144.756, 140.403, 129.325, 125.221, 120.112, 108.650, 106.659, 106.253, 104.879, 101.621, 55.608 (OCH3); Infrared Spectrum Vmax (KBr)/cm−1 1668.3 (C═O); Mass Spectrum (FAB) m/e 313 (m+1); Elemental Analysis: Molecular Compound C18H16O5, calculated C=69.23, H=5.19 and found C=69.15, H=5.18.

Provenance & Evidence