[g-bones]

Can someone tell show me the structure of a BzO group or at least tell me what it is?  I came across it as a leaving group in palladium allyl chemistry (similar to OAc or OCO2Me). I am assuming it would be just benzoyl wouldn't it? good delocalization of negative charge making it a good leaving group? here is an example of its use in total synththesis.

[agrobert]

http://en.wikipedia.org/wiki/Benzoyl

[lutesium]

As far as I can imagine its not a good leaving group but it may form a complex with the Pd catalyst and upon deprotonation of a-Carbon of the Carboxylic Acid w/LDA it may also bond to the catalyst by oxidative addition and upon reductive elimination of these two molecules the product + Bz-OH occurs. These are just guesses (I have got no references)...

Tried to help.


Lutesium...

[g-bones]

As far as I can imagine its not a good leaving group but it may form a complex with the Pd catalyst and upon deprotonation of a-Carbon of the Carboxylic Acid w/LDA it may also bond to the catalyst by oxidative addition and upon reductive elimination of these two molecules the product + Bz-OH occurs. These are just guesses (I have got no references)...

Tried to help.


Lutesium...

Thanks for your help.  i respectfully disagree though because OAc groups have been shown to be great leaving groups in palladium-allyl chemistry (as well as other eta-3 complex forming metals). the reason it is a good leaving group is because the negative charge it would form would be delocalized onto the oxygen on the carbon over (like a carboxylic acid), as well as being near an EW phenyl group.  the LDA is there to deprotonate the other, huge reagent, between the ester and the amide, forming a nucleophile, nucleophilic enough to attack the palladium eta-3 complex but soft enough to minimize elimination (due to basicity)

[lutesium]

If you know it why are you asking then
For verification purpoes?

Lutesium...

[lutesium]

But as much as I know Bz groups are used are protecting groups. And even upon hydrogenation it leaves a OH- + BzOH. I still insist that it has got something to do with Pd catalyst.


Lutesium...

[movies]

G-bones is right on this one.  Carboxylates are good leaving groups for the formation of palladium pi-allyl complexes.  Certainly acetates are more common, however.

Also, benzoates are not reactive under hydrogenation conditions.  Benzyl ethers will be cleaved (to toluene + HO-R).

[g-bones]

If you know it why are you asking then
For verification purpoes?

Lutesium...

haha I asked because i didnt know what a BzO group was, but once I found out from agrobert's post, it all made sense.