Bondline / Reactions

Conjugate (Michael) addition

Soft nucleophiles add to the end carbon (β-carbon) of a C=C–C=O system. The enolate formed is then protonated on carbon.

Enolates · 2 steps

Conditions

α,β-Unsaturated carbonyl with a soft nucleophile (CN⁻, enolates, R₂CuLi, thiols, amines).

Mechanism in 2 steps

Red curly arrows show where each pair of electrons moves.

NONO−HOH++
Step 1Cyanide attacks the β-carbon; the electrons move along to the oxygen, giving an enolate.
NO−HOHNOHO−H₂O++
Step 2The enolate is protonated on carbon as the C=O reforms.

About enolates reactions

A C–H next to a carbonyl is acidic, because the anion formed (an enolate) is stabilised by resonance. Enolates are carbon nucleophiles that make new C–C bonds.

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