Allyl bromide → Methyl 2-Allyl-3-hydroxy-5-methoxybenzoate

Participants

Reaction Steps

4-Allyl-3,5-dimethoxy-benzoyl chloride. Starting from 3-hydroxy-5-methoxybenzoic acid methyl ester by reaction with allyl bromide, 3-allyloxy-5-methoxybenzoic acid methyl ester is prepared. B.p. 128°-30°C/0.4 mmHg. This compound is subjected to the allylic rearrangement performed as described by Tarbell in Organic Reactions, Vol. II, New York, 1944 and a mixture of 4-allyl-3-hydroxy-5-methoxybenzoic acid methyl ester and 2-allyl-3-hydroxy-5-methoxybenzoic acid methyl ester is obtained. By hydrolysis under alkaline conditions and separation by fractioned crystallization the pure 4-allyl-3-hydroxy-5-methoxybenzoic acid is obtained. M.p. 202°-3°C (from methanol). The reaction with dimethylsulfate according to the procedure described by F. Benington et al. in Journal Org.Chem. 25, 2066, 1960 affords the corresponding 4-allyl-3,5-dimethoxy-benzoic acid. M.p. 188°-90°C (from light petroleum). This compound is allowed to react with thionyl chloride and 4-allyl-3,5-dimethoxy-benzoyl chloride is prepared. M.p. 56°-57°C (from light petroleum).

Provenance & Evidence