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Loz

Isomerisation of substituted pyrazole?

Alexander Mathey  Follow

The intermediate carbonium ion with positive charge alpha to the carbonyl group is very unstable. The formation of the second isomer may be due to a sigmatropic reaction undergone by the intermediate.

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Chris Forgan  Follow

Abel J S C Vieira can you suggest some ways to control the isomer formation. I have observed that the isomer is less (< 2%) observed when the reaction is done in methanol and more in toluene (~20 %)

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Dennis Leppin  Follow

The solvent effect seems to exclude a sigmatropic migration. Maybe a neighbor group participation can be considered. Is the isomers ratio sensitive to the temperature of the reaction?

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