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 language | English |
|---|---|
| Pages (from-to) | 2961-2967 |
| Number of pages | 7 |
| Journal | Journal of Organic Chemistry |
| Volume | 43 |
| Issue number | 15 |
| Publication status | Published - 1978 |
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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 journal › Article
}
TY - JOUR
T1 - Dimerization of terminal epoxides by homogeneous transition-metal complexes. A novel synthesis of carboxylic esters
AU - Blum, Jochanan
AU - Zinger, Baruch
AU - Milstein, David
AU - Buchman, Ouri
PY - 1978
Y1 - 1978
N2 - 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.
AB - 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.
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M3 - Article
AN - SCOPUS:0345186631
VL - 43
SP - 2961
EP - 2967
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 15
ER -