[riina]

Hi,
So I came across this forum by finding this post on google :
http://www.chemicalforums.com/index.php?topic=4207.0

I am currently setting up doing the same reaction for my undergrad research project, and I'm just having a bit of a struggle working out part of the reaction mechanism.

So basically I will be making 2-acetyl-1,2,3,4-tetrahydro-beta-carboline, and I know the full process for this, but I can't work out how the decarboxylation of the carboxylic acid after the pictet-sprengler reaction works.
I have worked out the full reaction mechanism from tryptamine to 1,2,3,4-tetrahydro-beta-carboline-1-carboxylic acid, with the use of KOH and water, but my mind is just hitting a blank as to how the decarboxylation works. If I'm right, the HCl is used to stabilise the intermediate, but I can't work out the mechanism.

I really don't want an answer as such, more of a helpful explanation as to how I can work it out myself!

Many thanks!

[trinitrotoluene]

Hi,
So I came across this forum by finding this post on google :
http://www.chemicalforums.com/index.php?topic=4207.0

I am currently setting up doing the same reaction for my undergrad research project, and I'm just having a bit of a struggle working out part of the reaction mechanism.

So basically I will be making 2-acetyl-1,2,3,4-tetrahydro-beta-carboline, and I know the full process for this, but I can't work out how the decarboxylation of the carboxylic acid after the pictet-sprengler reaction works.
I have worked out the full reaction mechanism from tryptamine to 1,2,3,4-tetrahydro-beta-carboline-1-carboxylic acid, with the use of KOH and water, but my mind is just hitting a blank as to how the decarboxylation works. If I'm right, the HCl is used to stabilise the intermediate, but I can't work out the mechanism.

I really don't want an answer as such, more of a helpful explanation as to how I can work it out myself!

Many thanks!

Check out the Wiki page on Pictet-Sprengler. Hopefully that will prod you in the right direction.

[riina]

Hey,
thanks or the reply. I totally understand the pictet-springler reaction. I know how the ring closes, but I don't know how the next step of the reaction removes the -COOH which is a decarboxylation not the p-s reaction.
My problem is that I can't work out the movement of protons and where electrons are moved for that step.

[spirochete]

Could you post a picture of the mechanism you understand so far, so we can see the step you're unsure about? It's much easier to read a series of structures than it is a big wall of text.