Iron(ii)-induced cycloisomerization of alkynes via “non-vinylidene” pathways for iron(ii)-indolizine and -indolizinone complexes

Abstract

Reactions between pyridine-functionalized alkynes and an Fe(II) precursor supported by 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane afforded the first Fe(II)-indolizine and -indolizinone complexes. Structural analysis and theoretical calculations revealed the existence of unconventional “non-vinylidene” pathways and challenged the generality of vinylidene intermediacy in Fe(II)-induced alkyne transformations.