Ibuprofen is an original pharmaceutical compound that was invented in the Research Laboratories of the Boots Pure Drug Company Ltd in Nottingham, UK. It is one of the major pharmaceuticals in the world as well as a source of scientific and academic interest in the noncommercial sphere. The abandonment of ibufenac was the second major crisis point in the project: phenylacetic acids had been eliminated by reason of side-effects in three clinically effective compounds not detected in laboratory testing. Attention in Boots Chemistry Research turned to one of the intermediates in the synthesis of ibufenac, 4-isobutylacetophenone, as a possible intermediate in the synthesis of propionic acids. The structure–activity comparisons of many of the compounds prepared and tested in the Boots laboratories have been discussed by Nicholson. Once the structure of the metabolites of ibuprofen had been determined, it was advantageous to devise synth.