1,2- vs 1,4-Addition in Carbonyl Compounds

α,β-Unsaturated carbonyl compounds contain a carbonyl group and an alkene in conjugation. This conjugation creates three resonance forms. As a result, the molecule has two likely electrophilic sites: the carbonyl carbon and the β carbon.

A nucleophile can attack either site. Attack at the carbony...

Recall that α,β-unsaturated carbonyl compounds are molecules with two functional groups—a carbonyl and an alkene—in conjugation with each other.

The conjugation results in resonance structures, and its hybrid form reveals two possible electrophilic sites: the carbonyl carbon and the β carbon.

Simple nucleophilic addition across the...