Synthesis of indolizine derivatives by the reaction of 2-(2′-pyridyl)-pyridinium ylides with ethylenic dipolarophiles

Abstract The reaction of 2-(2′-pyridyl)-pyridinium N-ylides with substituted ethylenes such as acrylonitrile and ethyl acrylate gave the corresponding tetrahydroindolizine derivatives in high yields. Tetrahydroindolizine derivatives were dehydrogenated by treating with tetrapyridinecobalt(II) bichromate [CoPy 4 (HCrO 4 ) 2 ] to give aromatic indolizines bearing cyano, aroyl, 2′-pyridyl, ester group at the different positions. Seventeen new indolizine derivatives were prepared.