4-Acetoxyconiferaldehyde → 4-Acetoxyconiferyl alcohol

Participants

Reaction Steps

4-Acetoxyconiferaldaldehyde was prepared in 94-96% yield by acetylation of coniferaldehyde with acetic anhydride/pyridine and then reduced with borane/tert-butylamine complex to give the corresponding alcohol, as follows. The 4-acetoxyconiferaldehyde was dissolved in methylene chloride to which borane/tert-butylamine complex (1.5 equiv) was added. The mixture was stirred at room temperature for 2 h, when TLC showed that the starting material had disappeared completely. The solvent was evaporated at 40° C. under reduced pressure. The residue was hydrolyzed with 0.5 M H2SO4 in ethanol/water (1:1) for 1.5 h. Most of the ethanol was removed by evaporation, and the product was extracted with ethyl acetate. The ethyl acetate solution was washed with saturated NH4Cl and dried over MgSO4. Evaporation of the ethyl acetate gave the product, 4-acetoxyconiferyl alcohol as a pale yellow oil (96% yield); 1H NMR (acetone-d6) δ 2.31 (3H, s, OAc), 3.83 (3H, s, OAc), 3.90 (1H, t, J) 5.5 Hz, γ-OH), 4.22 (2H, dt, J) 5.5, 1.7 Hz, γ), 6.38 (1H, dt, J) 15.9, 5.2 Hz, β), 6.58 (1H, dt, J=15.9, 1.7 Hz, α), 6.97 (2H, m, A5/6), 7.15 (s, 1H, A2); 13C NMR δ 20.5 (OAc), 56.2 (OMe), 63.1 (γ), 110.9 (A2), 119.5 (A6), 123.6 (A5), 129.3 (α), 131.4 (β), 137.2 (A1), 140.2 (A4), 152.3 (A3), 169.0 (OAc).

Provenance & Evidence