SYNTHESES OF DIBENZO(B,E)(1,4)DIOXIN DERIVATIVES VIA IRON COMPLEXES, AND FURTHER FUNCTIONALIZATIONS VIA DIRECTED METALATION

Double nucleophilic aromatic substitution reactions between (cyclopentadienyl)(eta-6-1,2-dichlorobenzene)iron(1 +) salts and substituted 1,2-benzenediols have been carried out under mild conditions to prepare [eta-6-dibenzo[b,e][1,4]dioxin]iron(1 +) complexes functionalized in the 1- or 2-position with an alkyl, aldehyde, carboxylic acid, methoxycarbonyl, carboxamide, or hydroxy group. 3-Methyl- and 4-methyl(eta-6-1,2-dichlorobenzene)iron complexes were treated with substituted 1,2-benzenediols to effect functionalization of both aromatic rings of the heterocycle. The dibenzodioxin ligands were liberated routinely by irradiation with ultraviolet light. Directed deprotonation of the free functionalized dibenzodioxins with an alkyllithium reagent followed by quenching with a variety of electrophiles yielded further derivatives, including two new isoindolone systems.