Chapter 19 Flashcards

1
Q

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

A

carbon nucleophiles; C-C bonds

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2
Q

enolate anions react with haloalkanes in … reactions

A

SN2

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3
Q

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

A

aldehyde; ketone; carbonyl addition reaction

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4
Q

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

A

enolate; water; beta-hydroxy aldehyde or ketone

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5
Q

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

A

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

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6
Q

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

A

alpha, beta-unsaturated aldehyde/ketone

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7
Q

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

A

beta-ketoester product

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8
Q

a dieckmann condensation is an … of a diester

A

intramolecular Claisen condensation

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9
Q

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

A

alpha beta-unsaturated carbonyl; beta-hydroxy carbonyl

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10
Q

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

A

beta-ketoester

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11
Q

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

A

secondary amine

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12
Q

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

A

beta-C

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13
Q

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

A

enols; enolate anions

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14
Q

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

A

SN2; methyl; primary haloalkanes

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15
Q

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

A

acid chlorides; acid anhydrides

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16
Q

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

A

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

17
Q

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.

A

methyl ketone

18
Q

the acetoacetic ester synthesis is useful for synthesizing … and …

A

monosubstituted; disubstituted acetones

19
Q

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

A

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

20
Q

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.

A

carboxylic acid; alkyl groups

21
Q

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

A

beta carbon; alpha beta unsaturated carbonyl specis

22
Q

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.

A

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

23
Q

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

A

aldol reaction; cyclic

24
Q

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

A

Gilman reagents

25
Q

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

A

nucleophilic

26
Q

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

A

enolate anions.

27
Q

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

A

forms more rapidly; accessible; stable