[paneri]

Can you please tell a method to synthesize these salts?
I have tried with toluene ,hexane and acetylonitrile but the amount we get is not sufficient...
We have used and iodide with protective silyl group on the other part of the molecule

Thanx

[Dan]

Is the problem poor conversion or side reactions?

Could you use a pokier phosphine, like Bu₃P?

[paneri]

Is the problem poor conversion or side reactions?

Could you use a pokier phosphine, like Bu₃P?

Have u tried it?why do u suggest it?It is a simple reaction theoritically but difficult in lab,it needs time for the salt to be crystallized..
Our issue is the low yield
We have as protecting group -OTBDPS on the other side.

[discodermolide]

Can you please tell a method to synthesize these salts?
I have tried with toluene ,hexane and acetylonitrile but the amount we get is not sufficient...
We have used and iodide with protective silyl group on the other part of the molecule

Thanx

You are talking about the salts, correct, not the ylid?
Making the salt is just a matter of mixing the halide with Ph3P in a solvent, usually acetonitrile or THF. The salt should precipitate out of solution.

[OC pro]

You are talking about the salts, correct, not the ylid?
Making the salt is just a matter of mixing the halide with Ph3P in a solvent, usually acetonitrile or THF. The salt should precipitate out of solution.
[/quote]

Often heating is required. And sometimes the crystallization is very difficult. The phosphonium salts separate out as an extra layer. Column chromatography in CHCl3/MeOH 10:1 mixture gave all salts in excellent purity.

[Dan]

Have u tried it?why do u suggest it?

I've made stabilised ylids with Bu₃P, which is a more reactive phosphine than Ph₃P, and the salts were highly cystalline. I suggested it because I thought that maybe poor conversion is the problem.

Our issue is the low yield

I understand that, what I asked you is why do you get a low yield?

For example: Is is because the conversion is poor? Is it because there are side reactions? Is it an isolation problem (e.g. difficult to crystallise)?

[orgopete]

Call me old fashioned, but how about showing us the reaction to which we are to make suggestions? For all I know, the iodide nucleophile being generated is what is screwing the reactions up.