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Author Topic: Knoevenagel Condensation mechanism (coumarin dereviative synthesis)  (Read 14851 times)

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Rakkoonn

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I'm trying to figure out the mechanism of the following reaction:



I was told that it's a Knoevenagel condensation in the first step and then a cyclisation occurs. If I apply this scheme to my reaction it will look like this:






It doesn't look right. How does the cyclisation go?
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Dolphinsiu

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It is not Knoevenagel condensation, it is just simply an aldol condensation.

     O                O         O                      O         O
     ll                 ll          ll                       ll          ll
R - C - H + HO - C - C - C - OH --->  HO - C - C - C - OH
                                                                ll
                                                                C - R

Then cyclisation(intra-esterification) follows and the product is resulted.
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AWK

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english

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I thought Knoevenagel didn't work too well with 3­° amines.  You only need a catalytic amount anyway.
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kiwi

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It is not Knoevenagel condensation, it is just simply an aldol condensation.

that is a Knoevenagel condensation. And as for post one, what do alcohols and acids do in acidic media?
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