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Ruthenium- and Rhodium-catalyzed Carbenoid Reactions of Diazoesters in Hexaalkylguanidinium-based Ionic Liquids

Ruthenium- and Rhodium-catalyzed Carbenoid Reactions of Diazoesters in Hexaalkylguanidinium-based... Hexaalkylguanidinium-based room-temperature ionic liquids were investigated as solvents for the cyclopropanation of styrene with diazoacetates catalyzed by Rh 2 (OAc) 4 or (Ru 2 (μ-OAc) 2 (CO) 4 )n. While the yields of the formed cyclopropanes are much lower compared to the reactions performed in dichloromethane, the diastereomeric ratio is not significantly affected by the change of the reaction medium. Immobilization of the catalysts is only partially successful. In contrast to this intermolecular reaction, the Ru-catalyzed formation of a β -lactam by an intramolecular carbenoid C-H insertion of an α-methoxycarbonyl-α-diazoacetamide occurs in high yield, similar to the Rh 2 (OAc) 4 -catalyzed reaction. The cis → trans isomerization of the resulting 1-tert-butyl-3-methoxycarbonyl-4-phenylazetidin- 2-one is accelerated in the ionic liquid N,N-dibutyl-N’ ,N’-diethyl-N’,N’-dihexylguanidinium triflate. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Zeitschrift für Naturforschung B de Gruyter

Ruthenium- and Rhodium-catalyzed Carbenoid Reactions of Diazoesters in Hexaalkylguanidinium-based Ionic Liquids

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References (4)

Publisher
de Gruyter
Copyright
Copyright © 2012 by the
ISSN
0932-0776
eISSN
1865-7117
DOI
10.1515/znb-2012-0408
Publisher site
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Abstract

Hexaalkylguanidinium-based room-temperature ionic liquids were investigated as solvents for the cyclopropanation of styrene with diazoacetates catalyzed by Rh 2 (OAc) 4 or (Ru 2 (μ-OAc) 2 (CO) 4 )n. While the yields of the formed cyclopropanes are much lower compared to the reactions performed in dichloromethane, the diastereomeric ratio is not significantly affected by the change of the reaction medium. Immobilization of the catalysts is only partially successful. In contrast to this intermolecular reaction, the Ru-catalyzed formation of a β -lactam by an intramolecular carbenoid C-H insertion of an α-methoxycarbonyl-α-diazoacetamide occurs in high yield, similar to the Rh 2 (OAc) 4 -catalyzed reaction. The cis → trans isomerization of the resulting 1-tert-butyl-3-methoxycarbonyl-4-phenylazetidin- 2-one is accelerated in the ionic liquid N,N-dibutyl-N’ ,N’-diethyl-N’,N’-dihexylguanidinium triflate.

Journal

Zeitschrift für Naturforschung B – de Gruyter

Published: Apr 1, 2012

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