Chapter 19 - Enolate Anions and Enamines

Claisen condensation

Claisen condensation

In a(n) ________, the base is RO2, with R selected to match the alkoxy groups on the ester starting material.

Enamines

________ are C- containing compounds "C- N bonds are produced via the interaction of an aldehyde or ketone with a secondary amine, most often pyrrolidine or morpholine.

electrophilic processes

The counterion provides a shielding effect that inhibits ________, which is increased by the aggregate structure of enolate anions in solution.

RO2

When ________ is employed as the base, the position of equilibrium for the initial enolate- forming step is much to the side of the beginning ester depending on relative acid- base strengths; hence, the modest quantity of enolate anion generated will have plenty of ester to react with.

Dehydration

________ can occur under aldol reaction conditions, or it can be accomplished by heating in acid, in which case the carbonyl tautomerizes to the enol form, the other (non- enol) OH group is protonated, and H2O departs with a proton to provide the a, b- unsaturated aldehyde or ketone.

aldol reaction

A(n) ________ produces b- hydroxyaldehyde or b- hydroxyketone.

carbonyl addition

In ________ reactions, enolate anions react with aldehydes, ketones, and esters.

Claisen condensation mechanism

The ________ involves the reaction of one ester molecule with a base to form an enolate, which then reacts as a nucleophile with another ester molecule to form a tetrahedral carbonyl addition intermediate, in which the.

SN2 reaction

In a(n) ________ with methyl and primary haloalkanes, enamines can be alkylated on the b- carbon.

Intramolecular aldol reactions

________ can be utilized to build five- or six- membered rings from dicarbonyl compounds (either aldehydes or ketones), which form preferentially to smaller or bigger rings that could form.

Enamines

________ are essential in synthesis because the b- carbon is a nucleophile due to C conjugation "The electron pair on nitrogen forms a C p bond with C.

aldol reaction

The ________ involves the nucleophilic addition of an aldehyde or ketone's enolate anion to the carbonyl group of another aldehyde or ketone.

Claisen condensation

The term ________ refers to involving two ester molecules reacting in base to give a b- ketoester product.

Aldol reactions

________ are easily reversible, especially in bases.

aldol reaction

A(n) ________ can be either basic or acid catalyzed.

aldol reactions

Equilibrium in ________ favors products in the case of aldehydes, whereas little product is frequently produced in the case of ketones.