Name: _________________________________

CHEM 332. Final Exam

Spring 2015 Prof Mary Watson

Please write your answers clearly in the boxes provided. If your answer is illegible or outside the box, it will not be graded. You may use the back of test pages for scratch work. You may use molecular models. Use of calculators, cell phones, headphones, or any other electronic device during this exam is prohibited. No notes or books may be used during this exam. You may raise your hand to ask a question if you are not sure what is being asked of you. There are 14 pages in this exam. Please check that your test has 14 pages before you begin. The last 2 pages are blank and may be used as scratch paper. Page 2 contains potentially useful IR and NMR spectral tables, as well as a periodic table. Page 3 contains the 20 common amino acids.

Question Points

1 _____ /17

2 _____ /10

3 _____ /16

4 _____ /15

5 _____ /12

6 _____ /14

7 _____ /16

Total _____ /100

1

Name: _________________________________

Approximate IR Absorption Frequencies Bond Frequency (cm–1) Intensity O–H (alcohol) 3650–3200 Strong, broad O–H (carboxylic acid) 3300–2500 Strong, very broad N–H 3500–3300 Medium, broad C–H 3300–2700 Medium C≡N 2260–2220 Medium C≡C 2260–2100 Medium to weak C=O 1780–1650 Strong C–O 1250–1050 Strong

Approximate 1H NMR Chemical Shifts

Hydrogen δ (ppm) CH3 0.8–1.0 CH2 1.2–1.5 CH 1.4–1.7 C=C–CHx 1.7–2.3 O=C–CHx 2.0–2.7 Ph–CHx 2.3–3.0 ≡C–H 2.5 R2N–CHx 2.0–2.7 I–CHx 3.2 Br–CHx 3.4 Cl–CHx 3.5 F–CHx 4.4 O–CHx 3.2–3.8 C=CH 4.5–7.5 Ar–H 6.8–8.5 O=CH 9.0–10.0 ROH 1.0–5.5 ArOH 4.0–12.0 RNHx 0.5–5.0 CONHx 5.0–10.0 RCOOH 10–13

Approximate 13C NMR Chemical Shifts Carbon δ (ppm) Alkanes

Methyl 0–30 Methylene 15–55 Methine 25–55 Quaternary 30–40

Alkenes C=C 80–145

Alkynes C≡C 70–90

Aromatics 110–170 Benzene 128.7

Alcohols, Ethers C–O 50–90

Amines C–N 40–60

Halogens C–F 70–80 C–Cl 25–50 C–Br 10–40 C–I –20–10

Carbonyls, C=O R2C=O 190–220 RXC=O (X = O or N) 150–180

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CHEM 332. Spring 2014 Organic Chemistry University of Delaware Prof. Donald Watson

Natural Amino Acid

H2N

OH

O

O

OHH2N

O

OH

OHO

H2NO

OH

OH

H2NO

OH

H2NO

OH

NH

HN NH2

H2NO

OH

NH2

H2NO

OHN

NH

H2NO

OH

NH

H2N

Me

O

OHH2N

O

OH

Me Me

H2NO

OH

Me

Me

H2NO

OH

MeMe

H2N

NH2

O

O

OHH2N

O

OH

NH2O

H2NO

OH

OH

H2NO

OH

Me OH

H2NO

OH

SH

H2NO

OH

S Me

H2NO

OHNH O

OH

Aspartic acid Glutamic acid Asp Glu D E

pKa= 3.7 pKa= 4.3

Acidic Amino Acids Basic Amino Acids

pKa'= 12.5pKa'= 10.5 pKa'= 6.1

Arginine Lysine Histidine Arg Lys His R K H

Phenylalanine Phe F

Hydrophobic or Aliphatic Amino Acids

Alanine Valine Leucine Isoleucine Ala Val Leu Ile A V L I

Serine Threonine Tyrosine Ser Thr Tyr S T Y

pKa= 13.0 pKa= 13.0 pKa= 10.1

Polar/ Hydrogen bonding Amino Acids

Sulfur containing Amino Acids

Methionine Cysteine Met Cys M C

pKa= 8.3

Flexible/inflexible Amino Acids

Glycine Proline Gly Pro G P

Glutamine Tryptophan Gln Try Q W

Asparagine Asn N

3

Name: _________________________________

1. (17 points) (a) Please complete the following table.

Fisher Projection of Acyclic Form Acyclic Line Angle Cyclic Line Angle

O

HO OH

HO

HO

D-fructose

OH

(b) Please draw a reasonable arrow-pushing mechanism for the isomerization of D-fructose to 1.

O

HO OH

HO

HO

D-fructose

Ca(OH)2, H2O O OHOH

HOOH

OH

1

*

* * *

*OH

4

Name: _________________________________

(1 – continued) (c) Please re-draw product 1, indicating the stereochemistry of each of the starred (*) carbons. If both the R and S stereocenters may be formed, please indicate this using a “squiggle bond.”

O OHOH

HOOH

OH

1

*

* * *

*

1 with stereochemistry indicated:

= squiggle bond

= hashed bond

= bold bond

(d) Please draw the following forms of 1, clearly showing the stereochemistry you have indicated in part (c). You may again use “squiggle bonds” where appropriate.

Fisher Projection of Acyclic Form Acyclic Line Angle Haworth Projection

(α-pyranose)

Lowest Energy Cyclic Chair Conformation

(α-pyranose)

5

Name: _________________________________

2. (10 points) Please draw the structure of the peptide RGD in its major protonation state at pH = 7. Denote stereochemistry.

6

Name: _________________________________

3. (16 points) Please consider the following [4+4] cycloaddition under thermal conditions. (a) Please complete the structure of the product. Denote stereochemistry where appropriate.

Me

Me

+

Me

Me

Δ

incomplete structure(Please complete!)

(b) Please draw a reasonable arrow-pushing mechanism for this reaction.

(c) Please explain your predicted stereochemistry in part (a) using Frontier Molecular Orbital Theory.

7

Name: _________________________________

4. (15 points) Please fill in the missing reagents for each transformation below. In some cases, more than 1 step may be required.

H2N

Me

O

OH H2N

Me

O

HN

OH

O

MeMe

MeO

O

Me

O

O

O

O

CH3

SS

CH3

CH3

CH3

OO

(a)

(b)

(c)

(d)

(e)

8

Name: _________________________________

5. (12 points) Please consider the following reaction of cyclopentadiene. Upon reaction with EtMgBr and then CH3I, product A forms. After sitting for 2–3 days at room temperature, A partially reacts to give a mixture of A and 2-methylcyclopentadiene (B) in approximately a 1:1 ratio. The 1H NMR spectra of A and B are shown on the next page. a) Please draw the structure of A.

i) EtMgBrii) CH3I

CH3

A, C6H8

room temp2–3 days

Δ A +

A : B ~ 1:1

B

b) Please draw a reasonable arrow-pushing mechanism for the formation of A.

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Name: _________________________________

(5 – continued) Please note: You do not need to see coupling patterns to figure out the answer!

A

B

3H

2H

1H

1H 1H

3H

2H

2H

1H

10

Name: _________________________________

6. (14 points) (a) Please provide a synthesis of 1 from benzene. You may use any additional reagents with less than 2 carbons.

H3C H

O

1

(b) Please provide a synthesis of 2 from 1. You may use di-tert-butyl dicarbonate, and any additional reagents with less than 2 carbons.

NHOH

O

O

OMe

MeMe

O O

O

O

O

Me

MeMeMe

MeMe

di-tert-butyl dicarbonate(Boc)2O

2

H3C H

O

1

H3C

11

Name: _________________________________

7. (16 points) Please provide a synthesis of 3 from acetone and benzaldehyde. All other carbons in your product must come from reagents with two or less carbons, but you may use any additional reagents to accomplish the necessary transformations.

H3C

O

CH3+

H

O

Ph HO

O

CH3

CH3Ph

3

12

Name: _________________________________

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13

Name: _________________________________

This page was intentionally left blank and may be used for scratch paper.

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