| abstract |
The invention relates to compounds of the formulae I, II and IX <CHEM> wherein R3 is -COOH or -COOR4; R4 is an alkyl with 1 to 6 carbon atoms; A is the substituents of its ring, each of which may be different or the same, and are selected from the group consisting of hydrogen, halogens, alkyl, hydroxy or alkoxy. X<+> is a Lewis acid X is halogen. The compounds are useful as intermediates and processes for their preparation are also disclosed. |