Johnson-Claisen rearrangement

The Johnson-Claisen rearrangement is a name reaction in organic chemistry that was named after William Summer Johnson and Ludwig Claisen . Johnson discovered this reaction in 1970, the double name with Claisen was chosen because of the mechanism. With this rearrangement an ester is synthesized.

Overview reaction

In this rearrangement, the orthoester reacts with an allyl alcohol via an acetal to form an ester .

mechanism

In the first step, an oxygen atom of the orthoester attacks a proton , whereupon an alcohol is split off. An allyl alcohol binds to the carbon atom of the cation . In the next step, an alcohol attacks a proton of the methyl group. A double bond is formed and another alcohol is split off. The rearrangement of electrons turns the ether into an ester .

Individual evidence

↑ William Summer Johnson, Lucius Werthemann, William R. Bartlett, Timothy J. Brocksom, Tsung-Tee. Li, D. John Faulkner, Michael R. Petersen: Simple stereoselective version of the Claisen rearrangement leading to trans-trisubstituted olefinic bonds. Synthesis of squalene. In: Journal of the American Chemical Society. 92, 1970, p. 741, doi : 10.1021 / ja00706a074 .
↑ L. Kürti , B. Czakó: Strategic Applications Of Named Reactions In Organic Synthesis . Elsevier Academic Press, USA 2005, pp. 226 .

[1] William Summer Johnson, Lucius Werthemann, William R. Bartlett, Timothy J. Brocksom, Tsung-Tee. Li, D. John Faulkner, Michael R. Petersen: Simple stereoselective version of the Claisen rearrangement leading to trans-trisubstituted olefinic bonds. Synthesis of squalene. In: Journal of the American Chemical Society. 92, 1970, p. 741, doi : 10.1021 / ja00706a074 .

[2] L. Kürti , B. Czakó: Strategic Applications Of Named Reactions In Organic Synthesis . Elsevier Academic Press, USA 2005, pp. 226 .