From: Karl.Swift$##$questintl.com
Date: Fri Oct 22 1999 - 08:48:30 EDT
Try some form or equivalent of the 'Tebbe reagent' (Synthesis 1991, 165).
The reagent works well for the methylenation of esters to produce vinyl
ethers.
andrea gansz <andrea.gansz$##$mail.uni-oldenburg.de> on 22/10/99 12:36:44
Please respond to andrea.gansz$##$mail.uni-oldenburg.de
To: Multiple recipients of list orglist <orglist$##$dq.fct.unl.pt>
cc: (bcc: Karl Swift/GB/QUES/ICI)
Subject: Re: ORGLIST: wittig reaction
hello orglist,
I think he´s talking about a lactone. If so, yes, it can be done (I o=
nce
did a Wittig-type reaction with glucono-1,4-lactone, DMF, threefold
excess of ethoxymethylcarbonylmethylenetriphenylphosphorane, 140 °C),=
but the yields are often poor (due to side-reactions) and you might hav=
e
to employ harsher reaction conditions (greater excess of reagent,
elevated temperature) than you would using in rxs with aldehydes or
ketones. How about Grignard (with exactly one eq. of grignard reagent t=
o
prevent disubstituion) and subsequent elimination as an alternative?
A.G.
"Ilfir R. Ramazanov" schrieb:
>
> Hello,
>
> I don't understand did you say about a cyclic ester with C=O group?=
>
> you wrote:
> bl> Dear colleagues,
> bl> I have a weird idea. wittig reaction can be easily performed on
ketone or
> bl> aldehyde. can anyone please tell me if is possible for a cyclic
ester?! if
> bl> not, is it because the reaction simply can't happen or fear of
hydrolysis
> bl> (saponification) that may take place?
> bl> Please advice and thanks in advance.
>
> bl> Regards,
> bl> barnabas
>
> Best regards,
> Ilfir R. Ramazanov, Ph.D.,
> Laboratory of Catalytic Synthesis
> Institute of Petrochemistry and Catalysis,
> pr. Oktyabrya, 141,
> Ufa, 450075, Russia.
>
> mailto:elf$##$anrb.ru
>
> Visit my homepage and find some QC software
> http://members.tripod.com/~ChemELF
>
> Visit our lab web page
> http://organomet.cjb.net
>
> 22.10.1999 16:35
>
> __________________
>
> ORGLIST - Organic Chemistry Mailing List
> Website and Archive: http://www.orglist.net/
> List coordinator: Joao Aires de Sousa (jas$##$mail.fct.unl.pt)
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