Synthesis
The general procedure for the synthesis of 4-fluorobenzoylformaldehyde from 4-fluoroacetophenone was as follows: selenium dioxide (6.70 g, 61.0 mmol) was added to a mixed solution of dioxane (100 mL) and water (3 mL) containing 4-fluoroacetophenone (8.43 g, 61.0 mmol). The resulting mixture was heated at 55 °C until selenium dioxide was completely dissolved. Subsequently, the reaction mixture was refluxed for 5 to 6 hours. After monitoring the completion of the reaction by thin layer chromatography (TLC), the mixture was filtered and the filtrate was concentrated under vacuum to obtain a viscous oily substance. Water (50 mL) was added to the oily substance and the resulting mixture was stirred for 12 hours. Afterwards, the solid formed was collected on a filter, washed with water (25 mL) and dried under vacuum to finally obtain 4-fluorophenylglyoxal (6.60 g, 85% yield).1H NMR (400 MHz, CDCl3) δ: 7.18 (m, 2H), 8.11 (d, 2H), no signal for aldehyde CHO was observed.
References
[1] Patent: WO2011/95625, 2011, A1. Location in patent: Page/Page column 94
[2] Tetrahedron Letters, 2017, vol. 58, # 7, p. 658 - 662
[3] Patent: WO2007/39821, 2007, A2. Location in patent: Page/Page column 16
[4] Journal of Heterocyclic Chemistry, 1981, vol. 18, p. 1651 - 1653
[5] Angewandte Chemie - International Edition, 2016, vol. 55, # 36, p. 10890 - 10894
