# Which double bond is more electrophilic : carbon-carbon or carbon-oxygen?

Question

Attempt

It seems to me that the carbon-oxygen bond would be more electrophilic due to the higher electronegativity of oxygen. Hence I believe $$\ce{CH3-}$$ should attack the carbonyl site. But this doesn't seem to be the case.

Is it because that the intermediate carbanion can undergo resonance with oxygen, had $$\ce{CH3-}$$ attacked carbon- carbon double bond?

What can be a valid reason?

• Google for gilmans reagenthttps://www.masterorganicchemistry.com/2016/02/05/gilman-reagents-organocuprates-what-theyre-used-for/ – Aditya suresh May 9 '20 at 8:43
• Your title doesn't match your question. You should have said "In a $\alpha,\beta$-unsaturated system.." An isolated $\ce{C=C}$ bond is not electrophilic. – Mathew Mahindaratne May 9 '20 at 8:44
• This may assist en.wikipedia.org/wiki/Reactions_of_organocopper_reagents – Waylander May 9 '20 at 9:14
• of course, C=C bond is less electrophilic when compared to C=O bond, but the CH3 group seems to attack the C=C bond due to 1,4-addition. detailed explanation below. – user93057 May 10 '20 at 8:00
• Here is useful info on Gilman reagents and conjgate addition: www-oc.chemie.uni-regensburg.de/OCP/ch/chb/oc5/… – user55119 May 19 '20 at 22:13