4-Methoxybenzyl alcohol → 4-Methoxybenzyl bromide

Participants

Reaction Steps

A solution of 4-methoxybenzyl alcohol (6.2 ml, 50 mmol) in dry ether (120 ml) was treated dropwise with phosphorus tribromide (2.07 ml, 22 mmol). The mixture was heated under reflux for 1 hour, cooled, washed twice with water, dried and the solvent was evaporated. The 4-methoxybenzyl bromide thus produced was added to a mixture of 4-bromo-1,2-dihydro-3,6-pyridazinedione (for a synthesis, see Example 3(a) above) (4 g, 21 mmol) and potassium carbonate (8.28 g, 60 mmol) in dry DMF (60 ml) and stirred overnight at RT. The mixture was diluted with ethyl acetate, washed 3 times with water, dried over magnesium sulfate and evaporated to low volume. Some solid was filtered off and washed with ethyl acetate. The filtrate was evaporated to dryness and the residue chromatographed on silica, eluting with 20% ethyl acetate/hexane and then 100% ethyl acetate. This gave the less polar of the two desired products (3.233 g), the more polar of the two desired products (1.626 g) and a mixture of these (1.351 g). Total yield 6.30 g, 70%.

Provenance & Evidence