This invention is concerned with compounds of the formula wherein one of R.sup.5, R.sup.6 and R.sup.7 is and R.sup.1 to R.sup.13, X.sup.1, X.sup.2, m and n are defined in the description, and all pharmaceutically acceptable salts and/or esters thereof. The invention further relates to pharmaceutical compositions containing such compounds, to a process for their preparation and to their use for the treatment and/or prevention of diseases which are modulated by PPAR.delta. and/or PPAR.alpha. agonists.