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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Telamond on October 18, 2009, 07:57:12 AM

Title: Help with mechanism
Post by: Telamond on October 18, 2009, 07:57:12 AM

I just can't see the pathway for the mechanism...

The Pd coordinates to the olefin creating a small plus charge, opening it up for an nu-attack... But I just can't see how it is formed.
The last step should just be an isomerization to the most stable double bond...

Any hints for how to obtain the first intermediate?

Title: Re: Help with mechanism
Post by: Dan on October 18, 2009, 02:28:50 PM

Quote from: Telamond on October 18, 2009, 07:57:12 AM

I just can't see the pathway for the mechanism...

The Pd coordinates to the olefin creating a small plus charge, opening it up for an nu-attack... But I just can't see how it is formed.

Ok, so your Pd coordinates to the double bond, making it electrophilic. Now you need to attack with the nucleophile... How would you normally draw the nucleophilic attack by an aromatic with an electron donating substituent? - eg Phenol + bromine...

Title: Re: Help with mechanism
Post by: Telamond on October 19, 2009, 06:53:55 AM

D:
I got it now... didn't think of that at all... I got stuck on the idea of that it was going to be a C-H activation somehow... :/

Title: Re: Help with mechanism
Post by: jinclean on October 19, 2009, 07:48:45 AM

Well the palladium(2+) is a oxidation reagent because the Heck reaction use the Pb(0) but in this way the Pd is +2.so the reaction is a oxidation-FC-eliminate reaction