REACTIONS OF IMINODIMAGNESIUM REAGENTS WITH 1,4-QUINONES: THEIR STRUCTURAL FACTORS GOVERNING THE MODES OF REACTIONS

Article abstract of DOI:10.1002/poc.610071008

Reactions of benzo-, naphtho- and anthraquinone derivatives (unsubstituted and substituted) with aryliminodimagnesium and aryloxymagnesium of a weak electron-donating ability were studied.In addition to the reduction products (quinhydrones and hydroquinones), nuclear substitution and condensation (with =C=O) products were formed.The efficiency of single electron transfer (SET) from ArN(MgBr)2, evaluated by the relative values of the difference between the oxidation and reduction potentials of the reactants (ΔE=E_ox-E_red), varies with the electron-accepting power of quinones. ΔE governs the modes of semiquinone appearance (ESR signals) and the relative amounts of the heat of reactions, reflecting the types and yields of the products.It is concluded that condensation products of both components are produced in the reactions of quinones with the lower SET efficiency by the presence of a fused benzene ring or MeO substituent.The structure-reactivity relationship proposed previously for reactions of various magnesium reagents is extended in the reactions with a variety of quinones even in cases of higher SET efficiency.