A series of 2-thiazolylamino-, 2-thiazolyloxy- and 2-thiazolylthio-arylacetic acid derivatives was prepared by condensation of thioamides with halo-acetals according to Hantzsch's method, and thioamides having the α-methylarylacetic acid moiety were conveniently obtained from haloaromatic nitro compounds by a combination of known methods. In the model reaction of O-phenyl thiocarbamate (XVIII) with chloro-diethylacetal, isolation of intermediates such as acyclic halo-compound (XIX) and 4-ethoxy-2-phenoxy-2-thiazoline (XX) clarified the reaction path for the formation of 2-phenoxythiazole (XXI). The analgesic and anti-inflammatory effects of the compounds studied were evaluated by using the acetic acid-induced writhing method in mice and the rat carrageenin paw edema method, respectively. 2- [4- (2-Thiazolyloxy) phenyl] propionic acid (XIVa) had the most favorable therapeutic ratio between activity and toxicity (in mice).