Application of Ullmann and Ullmann–Finkelstein reactions for the synthesis of N-aryl-N-(1H-pyrazol-3-yl) acetamide or N-(1-aryl-1H-pyrazol-3-yl) acetamide derivatives and pharmacological evaluation

Ullmann-type reactions are becoming a major tool in medicinal chemistry. In this article, we describe the use of these Copper-catalyzed reactions with various precursors, acyl-heteroarylamines or pyrazoles of interest for pharmacomodulation. To the medicinal chemist they offer new, usually untapped disconnection approaches to compounds of interest. They thus open the way to new original analogues of bioactive compounds possibly not patented, from common building-blocks. They also allow C to N bioisosteric replacements, which sometimes are synthetically challenging. We report for the first time the critical effect of acetylamino substituents on the regioselective arylation of unsymmetrical pyrazoles that are useful for medicinal chemists. Finally, we have applied this strategy to the design of novel AT1 receptor antagonists. Though this family has been extensively investigated in the past 30 years, N-arylation and C to N replacement made possible by Ullmann chemistry, can produce original antagonists.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ullmann-type copper-catalyzed reactions useful for acyl-heteroarylamines or pyrazoles diversification. ► New disconnection approaches to compounds and C to N bioisosteric replacements allow novel AT1 receptor antagonists. ► Acetylamino subtituant is critical for the regioselective arylation of unsymmetrical pyrazoles.