Diastereoselective heterogeneous catalytic hydrogenation of N-heterocyclesPart II. Hydrogenation of pyrroles

High diastereoselectivities were obtained in the heterogeneous catalytic hy drogenation of a chiral pyrrole derivative with complete conversion, in non -acidic medium. The effects of catalytic metals, temperature and solvents o n the conversion and the diastereomeric excess (d.e.) were investigated. In the hydrogenation of N-(1'-methylpyrrole-2'-acetyl)-(S)-proline methyl eat er over rhodium on carbon, in methanol, at 20 bar and room temperature (RT) the highest d.e. was 95%. This is a successful example of a diastereoselec tion in the saturation of pyrrole ring. (C) 2001 Elsevier Science B.V. All rights reserved.