Synthesis of pyrrole derivatives mediated by dicobalthexacarbonyl

Addition of α- and β-amino acid derivatives to the cobalt stabilized propargylic cation 2 gives dicobalthexacarbonyl complexes with an amino acid derivative at the propargyl position. Oxidation of the resulting complexes with Fe(III) produces propargyl amines 4. Intramolecular cyclization of 4 with LDA followed by oxidation of the crude product with DDQ affords pyrrole derivatives as the major products.