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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
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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.
9
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: _________________________________
This page was intentionally left blank and may be used for scratch paper.
13
Name: _________________________________
This page was intentionally left blank and may be used for scratch paper.
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