The invention is concerned with the compounds of formula I and pharmaceutically acceptable salts and esters thereof, wherein X, Q and R1 -R3 are defined in the detailed description and claims. The invention is also concerned with the compounds of formula Z and pharmaceutically acceptable salts and esters thereof, wherein R1-R3 are defined in the detailed description and claims. In addition, the present invention relates to methods of manufacturing and using the compounds of formula I and Z as well as pharmaceutical compositions containing such compounds. The compounds of formula I and Z are antagonists or partial agonists at the CRTH2 receptor and may be useful in treating diseases and disorders associated with that receptor such as asthma.