ae, sub-groups, preferences and examples thereof do not cover esters of hydroxy compounds wherein R2 is hydroxy and the ester is formed with the hydroxy group R2.In another particular embodiment, formula (I) and sub-formulae, sub-groups, preferences and examples thereof do not cover esters of compounds wherein R3 is hydrogen, R5 is an aryl group, R6 is an alkyl group, R2 is hydroxy and the ester i