Michael rxn (ochem)

[JustwantDDS]

---

Members don't see this ad.

So from what I understand the Nuc- attacks at the Beta carbon whenever we have a 1,4 conjugated ketone?
Is that the only time we see the Michael rxn?

Chad talked briefly about it, and his sheets says the nuc is usually R2CuLi or enolate ion?

What is an enolate ion?

 

[rnbaxter]

I'll try to explain.

The enolate carbanion is like a di-ketone with a H removed inbetween the 2 carbonyl groups via a base. Therefore, the - charge is inbetween the 2 carbonyl groups giving rise to resonance. Because of this - charge on the carbon in the middle of the 2 carbonyls this compound acts as a good Nucleophile.

In michael addition reactions you have this nucleophilic carbanion, that attacks the + portions of a,B-unsaturated carbonyl compounds. The B carbon is further away from the the electronegative carbonyl component so the addition occurs at this carbon instead of the closer alpha carbon.