mixing readily available carbonyl compounds, pyrroles, and nucleophiles with an indium catalyst was found to give β‐alkylpyrroles in a regiospecific manner. Removal of benzyl (Bn) and cumyl groups from the nitrogen atoms of the products enables access to nitrogen‐unsubstituted β‐alkylpyrroles (see scheme).
Indium-Catalyzed Regioselective β-Alkylation of Pyrroles with Carbonyl Compounds and Hydrosilanes and Its Application to Construction of a Quaternary Carbon Center with a β-Pyrrolyl Group
studies showed the following three aspects: (1) dipyrrolylalkanes produced in situ from the pyrrole and carbonylcompound are key intermediates, (2) the selective β-alkylation is attributed to the selective elimination of an α-pyrrolyl group from the dipyrrolylalkane intermediates, and (3) the indium Lewis acidcatalyst is indispensable for the progress of both stages.