Protection of benzaldehydes as cyclic acetalsProtection of benzaldehydes as cyclic acetals
SyntheticPage 775
Published Feb 24, 2015
To 2,5-dimethoxybenzaldehyde (1.0 g, 6.02 mmol) in 1,3-propanediol (1.75 mL, 24.2 mmol, 4 eq.) were added (MeO)3CH (0.75 mL, 6.86 mmol, 1.1 eq.) and Bu4N.Br3 (26 mg, 0.05 mmol, 0.01 eq.). After stirring at room temperature for 45 min the reaction was quenched with saturated NaHCO3 (5 mL) and H2O (20 mL). The mixture was then extracted with EtOAc (3 × 10 mL) and the combined organic fractions washed sequentially with 10% NaHCO3 (20 mL), H2O (4 × 20 mL) then dried (MgSO4) and concentrated in vacuo to give 2-(2,5-dimethoxyphenyl)-1,3-dioxane (1.35 g, 100%) as a colourless oil suitable for further use.