Synthesis of a library of 1,2,3,7-tetrasubstituted indolizines using poly(ethylene glycol) as soluble support

A library of 1,2,3,7-tetrasubstituted indolizines has been synthesized using poly(ethylene glycol) (PEG) as soluble polymer support. The PEG-bound pyridinium salts reacted with alkenes or alkynes in the presence of Et3N via 1,3-dipolar cycloaddition to give PEG-bound indolizine derivatives, which were cleaved by 1% KCN/MeOH to afford 1,2,3,7-tetrasubstituted indolizines in good to excellent yields.