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A 1,6-Conjugate addition attacks the delta carbon of an extended conjugated electrophile. The resulting extended enolate can be protonated at different sites; proton transfer or equilibration can favor a product retaining carbonyl–alkene conjugation.

Addition of an enolate or enol to an aldehyde or ketone, giving a beta-hydroxy carbonyl compound. Subsequent dehydration is a distinct step and gives an aldol condensation.

An aldol addition followed by water elimination, commonly producing a conjugated carbonyl compound. Identifying which carbonyl supplies the enolate distinguishes constitutional products.

Allyl chloroformate is $\mathrm{ClC}(\mathrm{O})\mathrm{OC}{\mathrm{H}}_2\mathrm{CH}=\mathrm{C}{\mathrm{H}}_2$. oxygen acylation of an enolate makes an allyl enol carbonate.

An ambident nucleophile can form a bond through more than one atom. An enolate can attack through carbon or oxygen; these give distinct products, although its resonance contributors describe the same ion.

An aldol addition organized through a boron enolate and a coordinated carbonyl partner. Enolate geometry and auxiliary-controlled facial selection jointly determine product stereochemistry.

carbon acylation of an ester enolate followed by deprotonation of the beta-dicarbonyl product. ketone-enolate acylation by an acid chloride is a closely related acyl-substitution strategy, although it is not the classical ester self-condensation.

Conjugate addition attacks a beta position in a conjugated electrophile and redistributes pi bonding, often generating an enolate. proton transfer then supplies a saturated carbonyl product.

An enolate is the conjugate base formed by removing an alpha proton from a suitable carbonyl compound. Oxygen-centred and carbon-centred resonance contributors help explain its ability to react at either site.

Reaction of an enolate with an acyl electrophile. carbon acylation of a ketone enolate gives a 1,3-diketone; O-acylation gives a different connectivity.

Enolate alkylation forms a carbon–carbon bond by attack of an enolate carbon on an alkyl electrophile, commonly through an SN2 reaction. Solvent, counterion, aggregation and electrophile identity affect competition with oxygen alkylation.

Preference for forming or reacting one enolate of a carbonyl compound with more than one alpha site. A less substituted kinetic enolate and an equilibrated more substituted enolate can give different carbon skeletons.

An enolate derived by deprotonation alpha to an ester carbonyl.

Finasteride is an unsaturated 4-azasteroid inhibitor of steroid 5α-reductase. Enzyme-generated reduction and enolate capture of oxidized cofactor give a covalent cofactor–inhibitor adduct; the protein itself need not be covalently modified.

An aldol reaction between two reactive sites of the same molecule. A tethered enol or enolate attacks a carbonyl group to close a ring; the tether, conformation and competing chemical reactions influence the product.

An enolate preferentially formed under conditions where deprotonation site selection is not equilibrated, often at a less hindered alpha carbon with a bulky strong base.

Lithium diisopropylamide is a strong, sterically hindered base used to generate enolates. Its low nucleophilicity toward many carbonyl substrates helps separate deprotonation from carbonyl addition.

A strong lithium amide base used for enolate formation.

oxidation of an enol or enolate can generate a carbon-centred radical that adds intramolecularly to an alkene. Further oxidation or oxygen capture determines the final functional group.

Journal of the American Chemical Society 118, 2359–2365. Radiolabel recovery, denaturation, purification and spectroscopy establish the cofactor adduct. Figure 7 compares enolate protonation with cofactor trapping. Slow dissociation/breakdown motivates a timescale-qualified description of inhibition.