AMINO ZINC ENOLATE CARBOCYCLIZATION REACTIONS - NEW ACCESS TO POLYSUBSTITUTED PIPERIDINE-DERIVATIVES

Various N-pent-4-enylglycine methyl esters have been submitted to carb ocyclization of their zinc enolates onto the unactivated double bond. The cyclization to substituted pipecolic esters is highly stereoselect ive. In most cases, substitution of the pent-4-enyl moiety on various sites leads to a single isomer, hence a way to di-, tri-, tetra-, or p entasubstituted piperidines.