From: Fredrik Thorstensson (freto$##$ifm.liu.se)
Date: Tue Jan 30 2001 - 13:25:20 EST
I have used the Paquette's procedure, and I have by trial and error foun=
d that Pb(OAc)4 must be in contact with the solution for rather long 16-2=
4 h. Shorter time is not efficiant.
Of course the method is not 100 % but after a flashcolumn (sometimes two)=
I usually get white cristalls.
/FT
Alison og Thomas Høyer wrote:
> I have found RCM to work fine for 5,6,7 and 8 membered rings, and it is=
known from the literature for larger rings.
> In my cases, succes of the RCM depended on the substrate being thorough=
ly purified.
> The catalyst decomposes rather quickly upon warming, so if the conversi=
on doesn't become total in a few hours, there is a problem.
> In cases with allylic and homo-allylic substitution, the reaction worke=
d just fine.
> Perhaps other functional groups in your compounds are the problem.
>
> Removal of the last traces of metal after the reaction is more of a pro=
blem. I have had no succes in following Paquette's procedure for oxidizin=
g Ruthenium in the crude product with lead tetraacetate.
> Other suggestions, anybody?
>
> Thomas Hoyer
>
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