4-Methoxybenzyl alcohol → 4-Methoxybenzyl bromide

Beteiligte Stoffe

Reaktionsschritte

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), refluxed for 1 hour, cooled, washed twice with water, dried and the solvent evaporated. The 4-methoxybenzyl bromide thus produced was added to a mixture of 4-bromo-1,2-dihydro-3,6-pyridazinedione (for a preparation, see B. Kasnar et al, Nucleosides & Nucleotides (1994), 13(1-3), 459-79 or Example 30(a)) (4 g, 21 mmol) and potassium carbonate (8.28 g, 60 mmol) in dry DMF (60 ml) and stirred overnight at room temperature. 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 gel, eluting with 20% ethyl acetate/hexane and then 100% ethyl acetate. This gave the less polar of the 2 desired products (3.233 g), the more polar of the 2 desired products (1.626 g) and a mixture of these (1.351 g). Total yield 6.30 g, 70%.

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