Intramolecular friedel-crafts acylation of a pendant chain cyclobutadiene complex: evidence for exo attack and formation of allyl-iron cations in cyclobutadiene tricarbonyliron.

Abstract

Intramolecular cyclization of tricarbonyl[(1,2,3,4-η)1,3-cyclobutadien-1-hexanoic acid]iron yields evidence for exo attack on the ligand rather than metal-assisted delivery of the electrophile. Evidence is presented for the ligand retaining considerable antiaromatic character.