Synthesis and platelet aggregation inhibitory activity of 6-isobutyl-alpha-methyl-3-pyridineacetic acid

2-(4'-Isobutylphenyl)propionic acid, ibuprofen, is an antiinflammatory agent which possesses moderate platelet aggregation inhibitory activity. It was therefore of interest to determine what effect the replacement of the phenyl group of ibuprofen by a 3-pyridyl ring would have on platelet aggregation inhibitory activity. As a result, 6-isobutyl-alpha-methyl-o-pyridineacetic acid (7) and its 2-chloro analogue 13 were synthesized. The key step in the synthesis of 7 and 13 involved the oxidative rearrangement of enol ether 11 to the carboxylic ester 12 with thallium trinitrate. The entire sequences of reactions for the synthesis of compounds 7 and 13 are described in detail. Platelet aggregation inhibitory evaluation of 7 and 13 showed 7 to possess activity equivalent to ibuprofen; however, 13 was devoid of platelet aggregation inhibitory activity at an equivalent dose.