亲核共轭加成是一种有关共轭不饱和有机化合物的加成反应。一般羰基化合物的化成反应多半是一般的亲核加成或1，2-亲核加成反应。简单的烯烃化合物由于缺乏极性，不会有1，2-亲核加成的反应性，但若用特殊的取代基去激活烯烃，就会有反应性。

α,β-不饱和羰基化合物（像环己烯酮）可以由共振结构推断β部位是亲电子部位，可以与亲核试剂反应。结构中有负电荷，会变成醇盐阴离子，这样的亲核加成反应称做亲核共轭加成或1，4-亲核加成。而最重要的活性烯烃是上述提到的共轭羰基和丙烯腈。

Nucleophilic conjugate addition is a type of organic reaction. Ordinary nucleophilic additions or 1,2-nucleophilic additions deal mostly with additions to carbonyl compounds. Simple alkene compounds do not show 1,2 reactivity due to lack of polarity, unless the alkene is activated with special substituents. With α,β-unsaturated carbonyl compounds such as cyclohexenone it can be deduced from resonance structures that the β position is an electrophilic site which can react with a nucleophile. The negative charge in these structures is stored as an alkoxide anion. Such a nucleophilic addition is called a nucleophilic conjugate addition or 1,4-nucleophilic addition. The most important active alkenes are the aforementioned conjugated carbonyls and acrylonitriles.