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Author Topic: Help identifying unknown by-product of Pictet-Spengler reaction.  (Read 1942 times)

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CaverKat

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Help identifying unknown by-product of Pictet-Spengler reaction.
« on: December 30, 2011, 05:04:36 PM »

(changed text colour to make it stand out a bit more)

Full experiment details here (free).  More information here
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It's the by-product of the preparation of this, aka, KAB8-1:


This is reaction (R1 = OMe; R2 = Ph):



Known intermediates:



Here's the Mass Spec:



And I'm just digging up the H-NMR.  It's currently well camouflaged within my computer.

Suggestions, thoughts, comments all appreciated!

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Dan

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Re: Help identifying unknown by-product of Pictet-Spengler reaction.
« Reply #1 on: December 30, 2011, 10:46:47 PM »

As you have the ChemDraw, can you paste in the MW of the compounds you've drawn, just so we don't have to calculate them all to compare to the MS?
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CaverKat

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Re: Help identifying unknown by-product of Pictet-Spengler reaction.
« Reply #2 on: December 30, 2011, 11:14:37 PM »

Ah.  How silly of me.  Apologies, and here they are:



I've also tried calculating with sodium and with a charge of 2+... I've been focusing on the 441 peak, because it's so close to my product, but I'm quite curious about the base peak at 921.  Analogues of this compound have been known to dimerize in the MS, though.

I have a feeling it's something to do with the ethoxy leaving groups part way through the Pictet-Spengler.  But not entirely certain.  Seems the NMR is on the lab computer, so I won't be able to get it for a couple of days. 
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