Formylation and bromination ortho to the hydroxy-group of 2-carbonylsubstituted phenols in the presence of titanium(VI)chloride

Abstract

Formylation with dichloromethyl methyl either and titanium(IV)chloride in dichloromethane, and bromination with bromine and titanium(IV)chloride in dichloromethane, of methyl 2,4-dihydroxybenzoate(16), methyl 2-hydroxy-4-methoxybenzoate(17), ethyl 2-hydroxy-4-methoxy-6-methylbenzoate(21), methylbenzoate(24), and 2-hydroxy-4-methoxyacetophenone (25) produce appreciable amounts of 3-substituted products. This selective substitution in the position ortho to the hydroxy-group is discussed in terms of a six-membered ring titanium complex.