Chem 352- Exam 2

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Hint 1

Borohydride Ketone Reduction (20.4):

Can attack aldehydes and ketones

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Hint 2

Nucleophilic Acyl Substitution (20.7):

RCOCl → RCH₂OH

R₂CO→R₂CHOH

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Hint 3

Organometallic Reduction (20.7)

Alum. Hydride Carboxyl Reduction (20.7)

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Hint 4

Alum. Hydride Amine Reduction (20.7)

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Hint 5

DIBAL-H Reduction:

Use to reduce esters

Must be run at -78°C

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Hint 6

"Lithium tri-tert-butoxyaluminum hydride" Reduction

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Hint 7

High-Pressure Catalytic Metal Reduction (20.4C)

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Hint 8

Standard-Pressure Catalytic Metal Reduction (20.4C)

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Hint 9

Cr⁶⁺ Oxidation of Aldehydes (20.8):

Oxidizes alcohols similiarly

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Hint 10

Cr⁶⁺ Oxidation of Alcohols (12.12)

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Hint 11

Tollens Reagent (20.8):

Oxidation of aldehydes

No mechanism

Selectively oxidize aldehyde to carboxylic acid

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Hint 12

Enantioselective Carbonyl Reduction (20.6):

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Hint 13

Enantioselective Carbonyl Reduction (20.6):

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Hint 14

Deprotanation Grignard (20.9)

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Hint 15

Organometallic new C-C bond (20.10)

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Hint 16

Organocuprate Synthesis (20.9)

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Hint 17

Gignard Reagent Synthesis (20.9)

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Hint 18

Organolithium Synthesis (20.9)

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Hint 19

Protection (20.12):

tert-butyldimethylsilyl

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Hint 20

TBAF Deprotection (20.12):

Tetra-n-butylammonium fluoride

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Hint 21

Organometallic Dialkylation (20.13) Acid Halide

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Hint 22

Grignard Nuceophilic Acyl Substitution (20.13):

MUST use (2 equiv.)

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Hint 23

Carboxylation (20.14)

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Hint 24

Expoxide Opening (20.14)

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Hint 25

1,2-Addition Grignard (20.15)

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Hint 26

1,4-Addition Organocuprate (20.15):

Uses Enolate path

Organocuprates add 1,4

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Hint 27

Alkyne Hydration (11.9)

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Hint 28

Cyanohydrin Formation (21.9)

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Hint 29

Cyanohydrin Revertion (21.9)

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Hint 30

Wittig Formation (21.10):

Z isomer (standard)

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Hint 31

Wittig Formation (21.10):

E Isomer (conjugated)

CAREFUL: Make sure there are no unprotected alcohols or carboxy groups on your wittig!

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Hint 32

Wittig Reaction (21.10):

[1] Ylide attacks carbonyl

Oxaphosphetane Inter.

Forming a 1° halide is easier than forming a 2°

Adds Z unless the product is conjugated than it forms E

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Hint 33

Imine Formation (21.11):

Formed from 1° amine

Carbinolamine interm.

Iminium Ion interm.

Also called a Schiff base

Requires pH 4-5

Every step is in equilibrium

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Hint 34

Formation of Enamines (21.12):

Formed from 2° amine

Forms E and Z isomers

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Hint 35

Enamine Hydrolysis (20.12)

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Hint 36

Imine Hydrolysis (20.12)

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Hint 37

Dioxalane Protection (21.14):

Carbonyl protection

Hemiacetal formation

Only occurs with ketones and aldehydes

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Hint 38

Acetal Formation (21.14):

Also with aldehydes

Reversible

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Hint 39

Hydrolysis (21.14):

Le Chatelier's Principle

Requires a strong acid

Carbonyl deprotection

Reversible

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Hint 40

Intramolecular Hemiacetal Formation (21.16):

Faster than intermolecular rxns.

Cyclic 5 or 6 carbon rings

Axial and equatorial isomers

Requires aldehydes

Reversible

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Hint 41

Hemiacetal to Acetals (21.16)

Reversible

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Hint 42

Oxidation

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Hint 43

Anhydride Amidification (22.9)

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Hint 44

Acid Chloride Hydrolysis (22.8)

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Hint 45

Acid Chloride Amidification (22.8):

Also works with alcohols

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Hint 46

Thionyl Chloride as Nu (22.10):

Pyridine deprotonates

NR with anhydrides

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Hint 47

Intramolecular Anhydride Formation (22.10B)

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Hint 48

Fischer Esterification (22.10C):

Will not work in the presence of a base (forms carboxylate anion)

Use strong acid

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Hint 49

Intramolecular Esterification (22.10C)

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Hint 50

Acidic Ester Hydrolysis (22.11)

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Hint 51

Saponification (22.11):

Basic ester hydrolysis

Resonance-stabilized carboxylate anion

Protonate with Strong HA

Not reversible

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Hint 52

Base-Catalyzed Amide Hydrolysis (22.13):

Not reversible

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Hint 53

Acid-Catalyzed Amide Hydrolysis (22.13)

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Hint 54

Cyano Reduction (22.18)

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Hint 55

Hindered Cyano Reduction (22.18)

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Hint 56

Cyano Gringard Rxn. (22.18)

Only adds 1 methyl

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Hint 57

Acidic Cyanohydrin Hydrolysis (21.9)

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Hint 58

Basic Cyano Hydrolysis (21.9):

[2] Imidic Acid

[3-4] Tautomerization to Amide

[2] Amide hydrolysis

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IR Absorption:

Acid Chloride

Anhydride

Ester

Amide

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1800 cm⁻¹

1820-1760 cm⁻¹

1735-1745 cm⁻¹

1630-1680 cm⁻¹

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H NMR Absorptions:

Amide N-H

Carbonyl Alpha C-H

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7.8-8.5 ppm

2-2.5 ppm