Chem 22 Spring 2001           Third Review Sheet

Reactions covered in Chapter 17

1. Catalytic hydrogenations

            H₂ + Pt, Pd, or Ni Reduces

                      Alkenes to                   _______________      Alkynes to             _______________

                       Imines to                    _______________      Nitriles to            _______________

                        Aldehydes to               _______________      Ketones to            _______________

                        Acyl halides to _______________

            Modified catalysts: deactivated to only perform a single reduction

                        Acyl halides to _______________ with the catalyst _______________

                        Alkynes to _______________ with the catalyst _______________

2. Dissolving metal reductions:

            Alkyne to cis-Alkene with ___________________________

            Aldehyde or ketone to alkane with ___________________________

            Nitro to amino with ___________________________

            Benzene to 1,4-cyclohexadiene with ___________________________

3. Hydride reductions: see Chapter 16 Review Reactions above.

            Also, LiAlH₄ can reduce:

            Nitro to 1° amine         Nitrile to 1° amine       Azide to 1° amine

4. Oxidation of oxygen-containing functional groups: no mechanism

            1° Alcohols oxidized to carboxylic acids by ___________________

            1° Alcohols oxidized to aldehydes by ___________________

            2° Alcohols oxidized to ketones by ___________________

            3° Alcohols cannot be oxidized. Why not?

            Aldehydes selectively oxidized to carboxylic acids by ___________________

            Ketones oxidized to esters (Baeyer-Villiger oxidation) by ___________________

                        migration tendency: ______________________________________

5. Alkene Hydroxylation: mechanism causes syn addition

Two sets of reagents can be used: ____________________ or

1)   ____________________ followed by 2) ____________________

Similar conditions with alkynes yields ____________________________

6. Oxidative cleavage of diols with ______________

Product determined by breaking C-C bond if each carbon is bonded to an oxygen.

Oxidize the carbon up one level (add a C-O bond) for each C-C bond cleavage.

7. Oxidative cleavage of alkenes;

Ozonolysis: Reagents for reductive workup

1)   ____________________ followed by 2) ____________________

Products will be ____________________________

Reagents for oxidative workup

     1) ____________________ followed by 2) ____________________

Products will be ____________________________

Products will be similar to oxidative ozonolysis workup when using_______________

Alkynes produce _______________ when subjected to ozonolysis

What happens to terminal alkene/yne carbons in each of these cleavage reactions?

8. Oxygen insertion for alkenes with peroxyacids: know the one step mechanism.

Common abbrieviation for two aromatic peroxyacids: _________ and _________

Product of reaction with alkenes is ______________________

This product may be turned into anti glycol (contrast with #1 above)

9. Quinone/Hydroquinone redox pair:

Reagents for oxidation: ___________________________

Reagents for reduction: ___________________________

Phenols are also oxidized to quinones with chromic acid.

Reactions Covered in Chapter 18

1.  Keto-enol tautomerizations: know acid and base catalyzed mechanisms.

      Be able to draw tautomers for oxygen and nitrogen-containing tautomeric systems.

2.   a-halogenation: Know acid and base mechanisms.

      Which favors mono-halogenation and which favors multiple halogenation?

      The haloform reaction forms carboxylic acids from __________________.

            Reagents in the haloform reaction: ___________________

      HVZ Reaction: converts carboxylic acids into___________________

            Reagents in the HVZ reaction: ___________________

3.   a-hydrogen exchange: Know acid and base mechanisms.

      Which positions exchange more readily?

4.   a-alkylation: Several possible methods.

LDA as base: for unsymmetrical ketones, this usually favors which product? _______

      For aldehydes, esters and nitriles, LDA is best method -- lack of selectivity

                  problems since only a single position may be alkylated

Weaker bases (OH^-, OR^-) may be used when the a-position is doubly activated.

Enamines can be used as a masked enolate. (Must be hydrolyzed after alkylation step.)

5. The Michael Reaction: Formation of 1,5-dicarbonyls. Know mechanism.

Starting materials _____________________ + _____________________

Reagents: _____________________

Stork enamine synthesis is a good substitute.

6.   The aldol addition and condensation: know base catalyzed mechanism.

Addition product: _________________ Condensation product: _________________

Starting materials _____________________ + _____________________

Reagents: _____________________

      Stops after addition without heat, unless condensation product is highly conjugated.

      Why can addition product be dehydrated with base?

Mixed aldols: when are they possible?

Intramolecular aldols: form products with ring size of ________________.

7. Kolbe synthesis of salicylic acid: know mechanism, starting materials, and reagents.

8. The Claisen condensation: know base catalyzed mechanism.

      Condensation product is always: _________________

Starting materials _____________________

Reagents: _____________________

      Starting material MUST have ____ a-hydrogens

Mixed Claisens: when are they possible?

Intramolecular Claisens (Dieckmann): form products with ring size of ____________.

      Be able to do retrosynthetic analysis on Claisen products.

9. Robinson Annulation: this sequence always forms products with ring size of _______.

Reactions involved: Step 1 ____________________ Step 2 ____________________

Starts with ________________ + ____________________ with ________________.

Know mechanism.

      Be able to do retrosynthetic analysis on Robinson products.

10. Decarboxylation of b-dicarbonyl compounds: know mechanism.

b-diesters or b-ketoesters may be hydrolyzed, made acidic, and heated to induce.

Used in malonic ester or acetoacetic ester syntheses. Reagents:______________

      Be able to do retrosynthetic analysis on decarboxylated products.

Concepts Covered in Chapter 17/18

1. Simple redox definitions for organic reactions: how can you tell if oxidation or reduction occurred?

2. The differences in the reduction mechanisms (hydrogenation vs. dissolving metal vs. hydrides).

3. Use of chromic acid oxidation as a chemical test.

4. Use of redox in functional group interconversion for multi-step synthesis.

5. Use of alkene and diol cleavages to determine alkene structures.

6. Keto-enol equilibria: Which form is more stable? What conditions might reverse this stability? (There are at least 3 possible reasons.) Also, when more than one enol can form, which one is more stable?

7. Acidity of the a-position: Which functional groups give the most acidic a-hydrogens? Which groups give the least acidic? Why is the a-position acidic at all?

8. Kinetic vs. Thermodynamic enolates: What conditions favor formation of each? Think about the base used, temperature, and structure to determine the answer.

9. Why is LDA used as good general base for enolate formation?

Concepts Covered regarding Biomolecules.

1.     Carbohydrates: Sections 19.1 - 19.5, 19.10 - 19.15.

Nomenclature and stereochemistry

Monosaccharides: aldoses and ketoses. The D and L families.

Selected disaccharides: how are the units linked?

Selected polysaccharides: how are the units linked?

Sugar hemiacetals: pyranoses and furanoses (reducing sugars)

            Mutatoration and the a- and b-forms.

Sugar acetals: glycoside forms (nonreducing sugars)

            the a- and b-links

2.     Lipids: Sections 23.1 - 23.6, 23.9 - 23.11

Terpenes and the isoprene rule

How are terpenes classified?

Be able to recognize isoprene units.

Steroids and steroidal hormones: What is the basic structure of all these compounds?

How is the isoprene rule related to these compounds?

3.  Amino acids, peptides, proteins: Sections 20.1 - 20.4, 20.7 - 20.11, 20.13 - 20.16.

Structure and classification of a-amino acids.

Concept of the isoelectric point and polyprotic acidity.

Peptide bonds (links): What are they? What are they like? How do they affect protein structure?

Laboratory synthesis of peptides:

      Amino protection: t-Boc group

      Carboxyl activation: DCC or ethyl chloroformate.

      Automated Merrifield Peptide synthesis.

4.Nucleic acids, DNA and RNA: Sections 24.1, 24.7 - 24.8, 24.13.

Base structures: purines _______, ________; and pyrimidines ________, ________

      H-bonded structures

Sugars: ribofuranose or 2-deoxyribofuranose

Phosphate groups: Where are they linked?

Nucleotides are ____________________. Nucleosides are ___________________.

Helical structures: Watson and Crick strucutres for DNA and RNA;

major and minor grooves