It is a type of condensation reaction that involves the condensation of an aldehyde or ketone with succinic ester in the presence of sodium ethoxide or Potassium ethoxide to yield unsaturated ester acid .
The complete reaction is as below.

The mechanism involves 3 steps , and firstly the succinate is treated with base to give the following resonance stabilized hybrid. A carboanion is formed firstly.

Step : I
Step 1 involves the condensation of carbanion and ketone.

Step : II
Step 2 shows a rearrangement and intramolecular cyclization to give a lactone-ester.

Step : III
The ring opening takes place to give the unsaturated ester acid.

Click here to earn by following simple surveys .
thank you for providing a step by step mechanism. I found it very useful. Looking at step 3 of the mechanism, The lactone ester was not properly drawn, there is an extra hydrogen. I also think there is a need to include a fourth step acid workup/quench. Once again thank you.
LikeLike
Our research team will surely work on your advice. Thanks a lot
LikeLike