Vanillylmandelic Acid → 4-Hydroxy-3-methoxymandelic acid (phenylmethyl) ester

Participants

Reaction Steps

To a mixture of 4.371 g (0.022 mole) of 4-hydroxy-3-methoxymandelic acid, 11 ml of triethylamine in 100 ml of acetone was added 3.13 ml (0.0265 mole) of benzyl bromide. The reaction mixture was stirred (magnetic stirring) and heated at reflux (oil bath) under a nitrogen atmosphere. After 5 minutes of heating the reaction mixture became cloudy. Thin layer chromatography (TLC) (silica gel, acetone/ethyl acetate 95:5) showed 50% of the starting material remaining after 5 hours. Additional triethylamine (2 ml) and benzyl bromide (1.5 ml) were added, and the mixture was heated at reflux for 4 hours. TLC still showed starting material present. Additional reagents were added (1.5 ml benzyl bromide and 2 ml triethylamine) and heating was continued for 14 hours. The triethylamine hydrobromide was removed by filtration, and the filter cake was washed with acetone (3×10 ml). The filtrate and washings were evaporated to give 17.6 g of a semi-solid residue. The residue was triturated with water (30 ml), and the product extracted with methylene chloride (4×15 ml) and dried (sodium sulfate). Evaporation of the solvent yielded 4.99 g of a light-brown oil which was triturated with hexanes (20 ml) to crystallize the product. The cream-colored solid was separated and washed with hexanes (3×10 ml) to give 3.351 g (53% yield) of the product. Estimated purity by TLC was 98% (hexanes/acetone 5:1).

Provenance & Evidence