[Scintillation]

Hi all!

Has someone ever done a Julia-Kocienski (or modified Julia reaction) that just didn't want to work correctly?

I've searched the whole forum for anything related to it, but there's no post. Here's what I've tried :

I want to replace the oxygen with a simple carbon, so I used the appropriate phenyltetrazolyl sulfone (PTSO2CH3). I deprotonate the reagent with LiHMDS in THF from 0 to room temp for 30 min, then I add the carbonyl substrate. First, I tested the reaction on alpha-tetralone. Since I got no conversion even when doing the reaction at room temp, I switched to a reactive aldehyde (i.e. hydrocinnamaldehyde) to make sure it was going to work. Conversion is complete within 30 min, but I only obtain a complex mixture of products possessing higher polarities than the original aldehyde. I thought these could be reaction intermediates, so I let the reaction go overnight, then I heated at reflux for an additionnal 2-hour period. I still can't obtain the olefin...

Thanks in advance for any comments!

M.

[enahs]

Try taking your substrate and sulfone together first, and then adding the base.


You also might want to try a larger counterion (a base with K) to better allow the open transition state.

[Åke]

Is there a particular reason for using Julia-Kocienski? Remember that you can use Schlosser modification of Wittig reaction in order to achieve E-selectivity.

[karbon]

Your deprotonated PT sulfone probably attacks another molecule of PT sulfone during your first step (the PT is electrophilic). I haven't exactly done these reactions before, but the deprotonation should still occur at very low temperature which will probably prevent the breakdown of your reagent. So add base at -78, wait, add ketone/aldehyde warm to rt.