Diastereoselective heterogeneous catalytic hydrogenation of N-heterocycles : Part II. Hydrogenation of pyrroles

Abstract

High diastereoselectivities were obtained in the heterogeneous catalytic hydrogenation of a chiral pyrrole derivative with complete conversion, in non-acidic medium. The effects of catalytic metals, temperature and solvents on the conversion and the diastereomeric excess (d.e.) were investigated. In the hydrogenation of N-(1′-methylpyrrole-2′-acetyl)-( S)-proline methyl ester 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 diastereoselection in the saturation of pyrrole ring.