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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: cheesewithwhine on November 22, 2013, 11:34:45 AM

Title: Olefin metathesis: can it be done with alkynes, and how does the mechanism work?
Post by: cheesewithwhine on November 22, 2013, 11:34:45 AM

I found a Grubbs metathesis reaction that is apparently followed by a H2 reduction. Since metathesis reactions involve a 4 member ring transition state, how does it work with alkynes? Some help with the mechanism will be much appreciated!

Title: Re: Olefin metathesis: can it be done with alkynes, and how does the mechanism work?
Post by: discodermolide on November 22, 2013, 12:04:12 PM

yes it can be done, perhaps a read here may help.
http://en.wikipedia.org/wiki/Alkyne_metathesis (http://en.wikipedia.org/wiki/Alkyne_metathesis)

and here

http://www.organic-chemistry.org/Highlights/2005/28March.shtm (http://www.organic-chemistry.org/Highlights/2005/28March.shtm)

Title: Re: Olefin metathesis: can it be done with alkynes, and how does the mechanism work?
Post by: orgopete on November 22, 2013, 01:01:46 PM

I don't have a contribution here, but the Wikipedia link disco provided raises a question. Do the aromaticity rules apply to the metallocyclobutadiene intermediates shown?

Title: Re: Olefin metathesis: can it be done with alkynes, and how does the mechanism work?
Post by: Dan on November 22, 2013, 02:33:22 PM

cheesewithwine: This is enyne metathesis (alkyne+alkene), not alkyne metathesis (alkyne+alkyne).