1 Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke O., Montréal, QC H4B 1R6, Canada.
2 Centre in Green Chemistry and Catalysis, Montréal, QC H3C 3J7, Canada.
3 Research and Development, Boehringer Ingelheim (Canada) Ltd., 2100 rue Cunard, Laval, QC H7S 2G5, Canada.

Pyrrole derivatives are natural organic molecules that are important to the pharmaceutical industry due to their occurrence in nature and their use in a wide range of medical applications. In general, non-symmetric, 1,2,5-triaryl-substituted pyrroles are prepared either by Paal-Knorr condensation or cycloaddition that present synthetic challenges particularly if late-stage functionalization is required. The present study describes a modular approach to synthesizing 1,2,5-triarylpyrroles containing three different arene substituents. Using pyrrole ester building blocks, a sequence of decarboxylative cross-coupling and C-H arylation provides unsymmetrical 1,2,5-triarylpyrroles in a regioselective, stepwise manner; the scope and limitations of the sequence are disclosed.