217314-37-9Relevant academic research and scientific papers
Cascade Synthesis of Pyrroles from Nitroarenes with Benign Reductants Using a Heterogeneous Cobalt Catalyst
Ryabchuk, Pavel,Leischner, Thomas,Kreyenschulte, Carsten,Spannenberg, Anke,Junge, Kathrin,Beller, Matthias
supporting information, p. 18679 - 18685 (2020/09/02)
A bifunctional 3d-metal catalyst for the cascade synthesis of diverse pyrroles from nitroarenes is presented. The optimal catalytic system Co/NGr-C@SiO2-L is obtained by pyrolysis of a cobalt-impregnated composite followed by subsequent selective leaching. In the presence of this material, (transfer) hydrogenation of easily available nitroarenes and subsequent Paal–Knorr/Clauson-Kass condensation provides >40 pyrroles in good to high yields using dihydrogen, formic acid, or a CO/H2O mixture (WGSR conditions) as reductant. In addition to the favorable step economy, this straightforward domino process does not require any solvents or external co-catalysts. The general synthetic utility of this methodology was demonstrated on a variety of functionalized substrates including the preparation of biologically active and pharmaceutically relevant compounds, for example, (+)-Isamoltane.
2,5-dimethylpyrrole protection facilitates copper(I)-mediated methoxylations of aryl iodides in the presence of anilines
Ragan, John A.,Makowski, Teresa W.,Castaldi, Michael J.,Hill, Paul D.
, p. 1599 - 1603 (2007/10/03)
Converting iodoanilines to the corresponding 2,5-dimethylpyrroles was found to facilitate CuCI-mediated methoxide substitution. Examples with ortho-, meta-, or para-relationships between the iodide and aniline are presented. Several other aniline blocking groups were investigated and found not to be successful in this sequence.
