Thermally Induced Intramolecular Oxime Olefin Cycloadditions (IOOC) Leading to N-Bridgehead Systems. Stereochemistry and Molecular Mechanics Calculations

The intramolecular oxime olefin cycloaddition (IOOC) of proline and pipecolinic acid derivatives proceeds thermally with a high degree of stereoselectivity to provide a new route to functionalized pyrrolizidines, indolizidines, or quinolizidines. The ring closure proceeds with simultaneous stereoselective introduction of three or four stereocenters. Molecular mechanics calculations have been refined to accurately predict not only which stereoisomer is preferred but also the syn and anti coupling constants in these tricyclic molecules.