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Topic: need help with reaction  (Read 6826 times)

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Offline orgopete

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Re: need help with reaction
« Reply #15 on: May 24, 2012, 04:31:24 PM »
Can you post the actual reaction or at least a partial structure?

With 30 mg, don't use any of it. You are at the stage that you need to run model compounds to ensure the reaction is going to work before you common any of your 30 mg. At least to increase the odds. Either that, or start from scratch again. We don't know if you just used a bad reagent, solvent, technique, etc. Errors come in all shapes and sizes. You need to ensure there wasn't one.
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Offline discodermolide

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Re: need help with reaction
« Reply #16 on: May 24, 2012, 04:37:42 PM »
what do you mean by mixed anhydride


As a prospective Masters candidate you should know this.
RCH2-O(C=O)OR1
This reacts  with nucleophiles at the carbon of the RCH2-O group to give CO2 +OR1+RCH2-nucleophile. R1 is usually Iso butyl or t- butyl.
« Last Edit: May 24, 2012, 04:50:24 PM by discodermolide »
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Offline discodermolide

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Re: need help with reaction
« Reply #17 on: May 24, 2012, 04:52:58 PM »
Can you post the actual reaction or at least a partial structure?

With 30 mg, don't use any of it. You are at the stage that you need to run model compounds to ensure the reaction is going to work before you common any of your 30 mg. At least to increase the odds. Either that, or start from scratch again. We don't know if you just used a bad reagent, solvent, technique, etc. Errors come in all shapes and sizes. You need to ensure there wasn't one.

Don't like model compounds, they usually work, but when you come to use your actual substrate the model conditions usually fail, at least in my humble opinion and experience.
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Offline fledarmus

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Re: need help with reaction
« Reply #18 on: May 24, 2012, 05:46:29 PM »
You might look at oxidizing your alcohol to a ketone and doing a Wittig reaction with (methylmethoxy)triphenylphosphonium bromide. I'm not sure your alkene will surface the subsequent conditions though.

Here is an example:


Offline Dan

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Re: need help with reaction
« Reply #19 on: May 24, 2012, 06:45:46 PM »
It might be useful to see some structure, and post your sulfonation conditions. I've never seen a tosylation/mesylation/triflation at <70% unless it's tertiary - something else must be going on.
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