Manganese(III) acetate induced cyclization of α-arylalkyl and α-(aryloxy)alkyl β-dicarbonyl derivatives

Attilio Citterio, Daniele Fancelli, Claudia Finzi, Luca Pesce, Roberto Santi

Research output: Contribution to journalArticlepeer-review

Abstract

The oxidation of the title compounds by manganese(III) acetate in acetic acid at 50-80°C affords products of intramolecular aromatic alkylation. High yield and selectivity are observed in six-membered ring closures, whereas five- and seven-membered ring closures are associated with side products of dimerization and/or hydrogen abstraction. The aromatic substitution is favored in all cases by a high electron density of the aromatic carbon atom a to the carbonylalkyl substituent. The activation parameters for the oxidative cyclization of diethyl α-(2-naphthoxyethyl)malonate were determined (ΔH = 25.2 ± 0.3 kcal/mol, ΔS = 2.1 ± 0.5 cal/K mol). The reaction is interpreted to proceed through electrophilic Mn(III)-complexed β-dicarbonylalkyl radicals, formed by reversible inner-sphere electron transfer of Mn(III) carbonyl complexes, which add reversibly to the aromatic ring.

Original languageEnglish
Pages (from-to)2713-2718
Number of pages6
JournalJournal of Organic Chemistry
Volume54
Issue number11
Publication statusPublished - 1989

ASJC Scopus subject areas

  • Organic Chemistry

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