Dimerization of terminal epoxides by homogeneous transition-metal complexes. A novel synthesis of carboxylic esters

Jochanan Blum, Baruch Zinger, David Milstein, Ouri Buchman

Research output: Contribution to journalArticle

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Abstract

Terminal epoxides have been shown to dimerize to carboxylic esters at 180°C in the presence of some Rh(I) and Ru(II) catalysts. Mixing of two epoxides of different electronic nature gives as the main product "crossed" esters, in which the electron-donating substituents are attached to the carboxylic part and the electronegative groups to the alcoholic residue. Kinetic measurements were carried out using styrene oxide as substrate and RuCl2(PPh3)3 as catalyst. The reaction rate proved to increase either by increasing the electron density of the metal or by introduction of electron-donating groups in the substrate. The proposed reaction mechanism includes (a) dissociation of RuCl2(PPh3)3; (b) oxidative addition of the epoxide (through the less-substituted carbon atom) to the activated catalyst; (c) slow hydrogen transfer from the metal to the β-oxirane carbon, followed by ring cleavage of the epoxide; (d) α-hydrogen transfer and formation of a ruthenium-acyl complex; (e) addition of the second epoxide molecule to the acyl carbonyl carbon; (f) reductive elimination of ester RCH2CH2OCOCH2R from the rearranged ruthenium complex.

Original languageEnglish
Pages (from-to)2961-2967
Number of pages7
JournalJournal of Organic Chemistry
Volume43
Issue number15
Publication statusPublished - 1978

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Dimerization
Epoxy Compounds
Coordination Complexes
Transition metals
Esters
Ruthenium
Carbon
styrene oxide
Catalysts
Hydrogen
Metals
Ethylene Oxide
Electrons
Substrates
Reaction rates
Carrier concentration
Atoms
Molecules
Kinetics

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Dimerization of terminal epoxides by homogeneous transition-metal complexes. A novel synthesis of carboxylic esters. / Blum, Jochanan; Zinger, Baruch; Milstein, David; Buchman, Ouri.

In: Journal of Organic Chemistry, Vol. 43, No. 15, 1978, p. 2961-2967.

Research output: Contribution to journalArticle

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