Return to Contents Chapter 21: Ester Enolates Ch 21 contents

Decarboxylation of b-carbonyl esters

decarboxylation removes CO2
Reaction type: Hydrolysis then Elimination


Step 1:
Remember curly arrows flow.... Start at the protonation of the carbonyl, break the O-H bond and form the p bond, break the C-C and make the C=C. Note the concerted nature of this reaction and the cyclic transition state.
decarboxylation of malonic acid
Step 2:
Tautomerisation of the enol of the ketone leads to the more favourable ketone form (mechanism not shown here).

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organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary