Formylation and bromination ortho to the hydroxy-group of 2-carbonyl-substituted phenols in the presence of titanium(IV) chloride was written by Cresp, T. M.;Sargent, M. V.;Elix, J. A.;Murphy, D. P. H.. And the article was included in Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) in 1973.Electric Literature of C9H10O4 This article mentions the following:
Formylation with Cl2CHOMe-TiCl4 of Me 2,4-dihydroxybenzoate, Me 2-hydroxy-4-methoxybenzoate, Et 2-hydroxy-4-methoxy-6-methylbenzoate, Me 2-hydroxy-4-methylbenzoate, and 2-hydroxy-4-methoxyacetophenone gave the 3-formyl derivatives as the major products. Bromination in the presence of TiCl4 gave similar results. Formation of a six-membered ring Ti complex (e.g., I) induces selective substitution ortho to the OH group. In the experiment, the researchers used many compounds, for example, Methyl 4-Hydroxy-2-methoxybenzoate (cas: 28478-46-8Electric Literature of C9H10O4).
Methyl 4-Hydroxy-2-methoxybenzoate (cas: 28478-46-8) belongs to esters. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. Acyl chlorides and acid anhydrides alcoholysis is another way to produce esters. Acyl chlorides and acid anhydrides react with alcohols to produce esters. Anydrous conditions are recommended since both acyl chlorides and acid anhydrides react with water.Electric Literature of C9H10O4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics