Thermodynamics (more substituted alkenes)

Kinetics (carbanions move away from electron-pushing groups)

Acidity generally stays at one substitution

Basic polysubstitution (haloform reaction)

1. Active halogenated hydrocarbons used: 1RX, PhCH2X, allyl halogenated hydrocarbons, ketones, α-halogenated acid esters

2. Application of ethyl acetoacetate in synthesis

3. Diethyl malonate

①Aldol condensation of ketones

②Aldol condensation with α-H and without α-H

③Influence of conjugation effect

④Aldol condensation of aromatic aldehydes and ketones

⑤Intramolecular aldol condensation

1,3-diketone

①Synthesis of 1,4-diketone (use of diethyl malonate)

② Dieckmann condensation of ester - intramolecular Claison condensation

Under strong base, α-halogenated acid esters are affinity added to aldehydes and ketones and then intramolecularly affinity substituted → α, β epoxy acid esters

Terminal olefins with electron-withdrawing groups are catalyzed by tertiary amines. Coupling reaction with aldehydes, ketones or imines to produce allyl alcohol (amine)

In a strong alkaline medium, the α-carbon of the quaternary ammonium salt forms a carbanion, and another hydrocarbon group migrates to the carbanion. At the same time, the quaternary ammonium salt is converted into a tertiary amine

In a strong base medium, the carbanion formed by the α-carbon of the ketone is nucleophilically substituted by another chlorinated or brominated α-C to form Cyclopropanone intermediate, which reacts with a strong base to form a carboxylic acid derivative (the strong base acts as a reactant to determine which carboxylic acid derivative is generated)

After the nucleophilic addition of formaldehyde and secondary amines in a weakly acidic medium, the carbocation formed by dehydration reacts with the α-carbon of aldehydes and ketones, carboxylic acids, esters, nitro compounds, and nitriles. As well as positional couplings with carbanion properties such as terminal alkynes and the ortho-para position of phenols.

Dimerization of aromatic aldehydes into α-hydroxyketones under CN- (major improvement: using VB1 instead of catalyzer

Aldehydes that do not contain α-H are half reduced to alcohols under the action of concentrated alkali, and are generally oxidized to acids.

After MIchael addition, intramolecular aldol condensation (or ketoester condensation ), forming a six-membered cyclic α, β-unsaturated ketone (or 1,3-cyclohexanedione)

1,4-addition of carbanions with α, β-unsaturated aldehydes and ketones

Sulfur Yelide

Use triethyl phosphite (C2H5O) 3P to replace the intermediate product of the reaction between triphenylphosphine and halogenated hydrocarbons The next reaction can be promoted by using ordinary NaOC2H5

1. The quaternary phosphonium salt generated by 2-level halogenated hydrocarbons and triphenylphosphine (Pph3) is under the action of extremely strong base (phLi, ​​ph3CNa, NaH, etc.) Eliminating hydrogen halide generates ylide, which has carbanion properties. Ylide eliminates triphenylphosphine oxide after affinity addition with the carbonyl group of aldehydes and ketones, and converts the carbon-oxygen double bond into a carbon-carbon double bond.

Active methylene compounds under the action of weak bases (NH3, RNH2, R2NH, PhNHNH2, pyridine) The formed carbanion reacts with the nucleophilic addition-elimination reaction of the carbonyl group to form a carbon-carbon double bond.

The α-C generated by the acid anhydride under the action of the corresponding acid salt (it is the carbon next to the carbonyl group~) Dehydration after nucleophilic addition to aromatic aldehydes Generate α, β-unsaturated aromatic aldehydes

α-bromo acid ester forms the carbonyl group of organozinc reagent and aldehyde and ketone under the action of Zn Addition-elimination reaction to form β-hydroxy acid ester , if further acid is added or heated, α, β unsaturated acid esters will be generated