Allyl bromide → Methyl 2-hydroxy-4-[(prop-2-en-1-yl)oxy]benzoate

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Reaction Steps

Scheme B shows methods for the preparation of the 2,4-dihydroxybenzamide starting materials. Methyl 2,4-dihydroxybenzoate (X) is reacted with allyl bromide to give methyl 2-hydroxy-4-allyloxybenzoate (XI) which is heated to produce methyl 2,4-dihydroxy-3-(2-propenyl) benzoate (XII). Reaction of XII with an appropriate amine in the presence of ammonium chloride gives the 2,4-dihydroxy-3-(2-propenyl)benzamide (XIII) which can be hydrogenated to the 3-propyl compound (XIV). Alternatively XII may be reacted with methylene iodide and triisobutylaluminum to give methyl 3-(cyclopropylmethyl)-2,4-dihydroxybenzoate (XV) which is then reacted with an appropriate amine in the presence cf ammonium chloride to give the 2-(cyclopropylmethyl)-2,4-dihydroxybenzamide (XVI).

Provenance & Evidence