Knorr- Rabe partial reduction of pyrroles: Application to the synthesis of indolizidine alkaloids

• Brendon S. Gourlay,
• John H. Ryan and
• Jason A. Smith

Beilstein J. Org. Chem. 2008, 4, No. 3, doi:10.1186/1860-5397-4-3

• Brendon S. Gourlay John H. Ryan Jason A. Smith School of Chemistry, University of Tasmania, Hobart, Australia CSIRO Division of Molecular and Health Technologies, Bag 10, Clayton South, Victoria, Australia 10.1186/1860-5397-4-3 Abstract Background The Birch reduction of electron rich pyrroles

• required bicyclic 3-pyrrolines and chose to explore accessing these intermediates via partial reduction of the corresponding pyrrole derivatives. These substrates were far more electron rich than those of Donohoe and thus not amenable to Birch reduction methodology. Therefore, we turned to an underutilised

• intermediate. Donohoe's approach to (±)-1-epiaustraline utilising a modified Birch reduction. Reaction conditions i) Zn, HCl (aq). Reaction conditions: i) ref. [10] ii) ref. [11] iii) Zn, conc. HCl(aq). Potential mechanism for α-ketopyrrole reduction.. Alternative reduction pathway. Catalytic hydrogenation