ORGLIST:RE: Mitsunobu Rxn & Fmoc

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From: Christopher Joseph Gorman (cjgorman$##$sas.upenn.edu)
Date: Thu Jul 22 2004 - 17:09:17 EDT


Hi,

Having some of any tri-substituted amine in solution should make the whole
thing
work. Here's why:

 (such as triethylamine, or pyridine) work, because Fmoc doesn't move generally
so long as the whole pot is overall kept at least somewhat basic -- and the
tri-substituted amine nucleophilic addition side reaction won't compete with
adding to the phosphorus (not irreversibly) -- If you look up the mechanism of
the Mitsunobu reaction you'll see what I mean -- I would make sure that your
pot doesn't have a prayer of hitting pH 7.0 or below as a main prerogative to
make your step go as smoothly as possible.

Hope that helps!

Chris

PS: (But you, of course, can't have too much base or the Ph3P-Br won't be
stable
enough to really form at all and last enough to do what you want). Good luck!

"The nature of the truth is fundamentally biased by the nature of our
experience."
      --C.J. Gorman (from personal email greeting)
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