Chapter 19

Question 1

despite their charge distribution, enolate anions react as … that create new … bonds, making enolate anions important for organic synthesis

Answer 1

carbon nucleophiles; C-C bonds

Question 2

enolate anions react with haloalkanes in … reactions

Answer 2

SN2

Question 3

in the aldol reaction, enolate anions derived from aldehydes or ketones react with a second molecule of … or … to give a … rxn and create a new C-C bond

Answer 3

aldehyde; ketone; carbonyl addition reaction

Question 4

the mechanism of the base-catalyzed aldol rxns involves initial deprotonation of the alpha-H in base to create an … anion, which attacks another aldehyde or ketone molecule to give a carbonyl addition intermediate which in turn reacts with … to create a … produce and regenerates the original base

Answer 4

enolate; water; beta-hydroxy aldehyde or ketone

Question 5

the mechanism of the acid-catalyzed aldol rxn involves an initial acid-catalyzed … to provide the … form; protonation of a second molecule on the carbonyl oxygen creates an electrophilic oxonium ion that is then attacked by the nucleophlic enol, followed by loss of a … to give the … product

Answer 5

keto-enol tautomerization; enol; proton; beta-hydroxy aldehyde or ketone

Question 6

the beta-hydroxy aldehyde/ketone products of aldol rxns are easily dehydrated and lose H2O to give an …

Answer 6

alpha, beta-unsaturated aldehyde/ketone

Question 7

the claisen condensation involves two ester molecules reacting in base to give a

Answer 7

beta-ketoester product

Question 8

a dieckmann condensation is an … of a diester

Answer 8

intramolecular Claisen condensation

Question 9

to become skilled at retrosynthetic analysis, it is important to recognize that the … and … functional groups are the characterstic products of an aldol rxn

Answer 9

alpha beta-unsaturated carbonyl; beta-hydroxy carbonyl

Question 10

for retrosynthetic analysis, the … functional group is the characteristic product of claisen/dieckmann

Answer 10

beta-ketoester

Question 11

enamines are formed through rxn of an aldehyde/ketone with a ..

Answer 11

secondary amine

Question 12

enamines are important for synthesis bc the … is a nucleophile by virtue of conjugation of the C=C bond with the electron pair on nitrogen

Answer 12

beta-C

Question 13

enamines resemble … and … in their rxns; yet harsh conditions are not required

Answer 13

enols; enolate anions

Question 14

enamines can be alkylated on the beta c in an … rxn with … and …

Answer 14

SN2; methyl; primary haloalkanes

Question 15

enamines can be acylated on the b-C by treatment with … and …

Answer 15

acid chlorides; acid anhydrides

Question 16

the acetoacetic ester synthesis consists of 5 synthetic steps: ‘
ethyl acetoacetate is converted to its … anion using one equivalent of a base like sodium alkoxide the anion is used as a nucleophile in an SN2 rxn with … or …., …, and ..
the alkylated acetoacetic ester is … using OH-
acidification gives the …
heating causes … to give the alkylated … product

Answer 16

enolate; methyl; primary haloalkanes; alpha-haloketones; alpha-haloesters; hydrolyzed; alkylated acetoacetic acid; decarboxylation; ketone

Question 17

For retrosynthetic analysis, a … is a characteristic product of the acetoacetic ester synthesis starting with ethyl acetoacetate, and other complex ketones can be derived from other b-ketoester starting materials.

Answer 17

methyl ketone

Question 18

the acetoacetic ester synthesis is useful for synthesizing … and …

Answer 18

monosubstituted; disubstituted acetones

Question 19

Malonic ester synthesis consists of 5 steps:
diethyl malonate is converted to its … anion using one equiv of sodium ethoxide
the anion is used as a nucleophile in an sn2 rx with … or …, …, and …
the alkylated acetoacetic ester is … using OH-
acidification gives the …
heating causes decarboxylation to give the … product

Answer 19

enolate; methyl; primary haloalkanes; alpha-haloketones; alpha-haloesters; hydrolyzed; alkylated acetoacetic acid; alkylated carboxylic acid

Question 20

For retrosynthetic analysis, a … with one or two… bonded to the a-carbon is a characteristic product of the acetoacetic ester synthesis starting with diethyl malonate.

Answer 20

carboxylic acid; alkyl groups

Question 21

in a Michael reaction, the .. carbon of a … species is electrophilic and able to react with certain nucleophiles, especially enolates

Answer 21

beta carbon; alpha beta unsaturated carbonyl specis

Question 22

The mechanism of the Michael reaction involves initial formation of an …in base and attack of the enolate nucleophile onto the…of the Michael acceptor to create a new resonance-stabilized …that is protonated on oxygen to create an …and regenerate the base; then …. completes the reaction.

Answer 22

enolate anion; b-carbon; enolate anion intermediate; enol; tautomerization to the keto form

Question 23

A Robinson annulation is a Michael reaction with an a,b-unsaturated ketone followed by an intramolecular… creating a … product.

Answer 23

aldol reaction; cyclic

Question 24

….undergo conjugate addition with a,b-unsaturated carbonyl compounds in a reaction that is closely related to the Michael reaction.

Answer 24

Gilman reagents

Question 25

Lithium diisopropylamide (LDA) is an extremely strong base that is not ….due to steric hindrance

Answer 25

nucleophilic

Question 26

One molar equivalent of LDA converts aldehydes, ketones, and esters completely to their ...

Answer 26

enolate anions.

Question 27

If a slight excess of LDA is used, no equilibrium is established among the alternative enolate anions and the predominant enolate is the one that … (the removed a-hydrogen is more ...). If a slight excess of carbonyl species is used, an equilibrium is set up in which the more ...of the alternative enolate anions predominates, a situation known as thermodynamic control

Answer 27

forms more rapidly; accessible; stable