Re: ORGLIST: Hydroxylamine

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From: Jonas Nilsson (jonni$##$ifm.liu.se)
Date: Thu Jul 01 1999 - 03:29:58 EDT


Some or all of your product could be Cbz-O-NH-Ac. What are the proposed
michaels addition?


Example of bad carbamate::
c-hexyl-NHOH + Boc2O -> c-hexyl-NHOBoc (39%) + c-hexyl-NBocOH (41%)

/jN

David Gauthier wrote:

> Hi everybody,
> I have some problem to do AcO-NH-Cbz from NH2OH HCl and then
> HO-NH-Cbz. The H NMR spectrum is very simple for all of these
compounds
> (maybe too simple !!!). I think that I don't have the right product
> because the Michael addition is problematic when I use MY AcO-NH-Cbz
> produced. That Michael addition is supposed to be quantitative !
> I made HO-NH-Cbz by mixing H2NOH HCl with Bn-O-CO-Cl in CH2Cl2 (with
a
> solution of NaHCO3 aq). Then, I made AcO-NH-Cbz by mixing the
> HO-NH-Cbz produced with Acetyl chloride in THF, and added dropwise a
> solution of NaOH 1N. The product seems clean on H NMR, but the next
> step (Michael add.) doesn't work.
> If you some ideas, or if you've seen papers about my problem, tell
me.
>
> Thank you very much
>
> David Gauthier
> MSc University of Sherbrooke
> Canada
> gauthier.david$##$videotron.ca
>

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