381725-55-9Relevant academic research and scientific papers
The stereochemistry of the reduction of cyclic enaminones
Wysocka,Przybyl
, p. 973 - 984 (2007/10/03)
The stereo- and regiochemistry of di-, tri-, and tetracyclic enaminones upon catalytic hydrogenation on Pd and Pt catalysts seems to be mainly a function of the catalyst and the medium. The highest stereoselectivity was observed for multiflorine on Pd/C in which 99% of equatorial alcohol were formed in this case, the formation of alcohols proceeds via a ketonic intermediate. On platinum, irrespective of the solvent used (EtOH, H2O, AcOH, HCl), the hydrogenation reaction proceeds through ketonic (piperidone system) and dehydro (pyridone system) intermediates. In EtOH or H2O solution, the dehydro product remains unchanged, whereas the ketonic intermediate is reduced to a mixture of epimeric alcohols. In HCl and acetic acid, both intermediates are hydrogenolyzed to a product with a methylene group, but the ketonic one is additionally reduced to a mixture of epimeric alcohols. Reductions with complex metal hydrides provide mixtures of epimeric alcohols with a predominance of equatorial orientation. The structures of products were determined by NMR spectroscopy and/or by GC-MS analysis.
