The present invention relates to compounds of the formula I, wherein A, Y, Z, R3 to R6, R20 to R22 and R50 have the meanings indicated in the claims, which are valuable pharmaceutical active compounds. Specifically, they are inhibitors of the endothelial differentiation gene receptor 2 (Edg-2, EDG2), which is activated by lysophosphatidic acid (LPA) and is also termed as LPA1 receptor, and are useful for the treatment of diseases such as atherosclerosis, myocardial infarction and heart failure, for example. The invention furthermore relates to processes for the preparation of the compounds of the formula I, their use and pharmaceutical compositions comprising them.
