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

Reactions of benzo-, naphtho- and anthraquinone derivatives (unsubstit uted and substituted) with arylimino-dimagnesium [ArN(MgBr)2] and aryl oxymagnesium of a weak electron-donating ability were studied. In addi tion to the reduction products (quinhydrones and hydroquinones), nucle ar substitution and condensation (with drop C=0) products were formed. The efficiency of single electron transfer (SET) from ArN(MgBr)2, eva luated by the relative values of the difference between the oxidation and reduction potentials of the reactants (Delta E = E(OX) - E(red)), varies with the electron-accepting power of quinones. Delta E governs the modes of semiquinone appearance (ESR signals) and the relative amo unts of the heat of reactions, reflecting the types and yields of the products. It is concluded that condensation products of both component s are produced in the reactions of quinones with the lower SET efficie ncy by the presence of a fused benzene ring or MeO substituent. The st ructure-reactivity relationship proposed previously for reactions of v arious magnesium reagents is extended in the reactions with a variety of quinones even in cases of higher SET efficiency.