Indolizin-2-ones, 5,6,7,8-tetrahydro

Hydrogenation of 85a gives the tetrahydro derivative (88). A cycloadduct (89) may be obtained with V-phenylmaleimide. Heating 85a in toluene results in formation of a dimer containing two indolizine parts easily distinguished one from the other by PMR spectroscopy. 

Shigematsu H., Shibata S., Kurata T., Kato H. and Fujimaki M. (1975) 5-Acetyl-2,3-dihydro-l//-pyrrolizines and 5,6,7,8-tetrahydro-indolizin-8-ones, odor constituents formed on heating L-proline with D-glucose. J. Agric. Food Chem. 23, 233-7. 

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