Metal ion-catalyzed Diels-Alder and hydride transfer reactions. Catalysis of metal ions in the electron-transfer step

Shunichi Fukuzumi, Kei Ohkubo, Toshihiko Okamoto

Research output: Contribution to journalArticlepeer-review

87 Scopus citations

Abstract

Rates of Diels - Alder cycloaddition of anthracenes with p-benzoquinone and its derivatives as well as rates of hydride-transfer reactions from 10-methyl-9,10-dihydroacridine to the same series of p-benzoquinones are accelerated significantly in the presence of metal ions in acetonitrile. An extensive comparison of the catalytic effects of metal ions in electron transfer from one-electron reductants (cobalt tetraphenylporphyrin and decamethyrferrocene) to p-benzoquinones with those in the Diels - Alder reactions of the quinones as well as the hydride-transfer reactions has revealed that the catalysis of metal ions in each case is ascribed to the 1:1 and 1:2 complexes formed between the corresponding semiquinone radical anions and metal ions. The transient absorption and ESR spectra of the semiquinone radical anion-metal ion complexes are detected directly in the electron-transfer reduction of p-benzoquinone derivatives in the presence of metal ions. The catalytic reactivities of a variety of metal ions in each reaction are well correlated with the energy splitting values of πg levels because of the complex formation between O2.- andMn+, which are derived from the gzz values of the ESR spectra of the O2.--Mn+ complex.

Original languageEnglish
Pages (from-to)14147-14155
Number of pages9
JournalJournal of the American Chemical Society
Volume124
Issue number47
DOIs
StatePublished - 27 Nov 2002

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