4-Hydroxybenzaldehyde → 5-(4-Hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione

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Reaction Steps

Condensation with Meldrum's acid is carried out according to the method of Bigi et al., Tetrahedron Lett. 42:5203-5205 (2001). A 2L pear-shaped flask was charged with 4-hydroxybenzaldehyde (50 g, 409 mmol) and water (400 mL). The flask was placed in a water bath at 75° C. and Meldrum's acid (62 g, 430 mmol) was added as a slurry in 400 mL of water. The reaction mixture was agitated for 2 hours and cooled in an ice bath for 2 hours. The product was collected by filtration and rinsed with cold water. After drying thoroughly, 95 g of adduct 1.1 was obtained as a fine yellow powder. 1H NMR (500 MHz, DMSO-d6) δ 9.75 (br s, 1H); 8.27 (s, 1H); 8.24 (d, 2H, J=10 Hz); 6.98 (d, 2H, J=10 Hz); 1.76 (s, 6H). MS ESI (pos.) m/e: 519.0 (2M+Na).

Provenance & Evidence