Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
Please write the first three letters of
your last name in the above boxes
Name:_______________________________
UT EID:_____________________________
Signature:____________________________
Grade ( + / - / 0 ):_____________________
1
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
CH 328 M Review:
1. Fill in the provided table with the appropriate reagents for the conversion of bromocyclopentane
to each of the following compounds (some products are formed as racemic mixtures).
(a)
(g)
(b)
(h)
(c)
(i)
(d)
(j)
(e)
(k)
(f)
2
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
2. NMR
Clarifications/Hints:
-The word “signal” always refers to an entire set of equivalent hydrogen atoms.
- Multiplicities greater than a Quintet can be referred to as Multiplet.
- A reference chart with chemical shifts can be found at the end of the exam.
a) In the following table please fill in the number of expected signals, their relative integrals and
the multiplicity that you expect for each signal.
Chemical Structure
Number of Signals
Relative Integrals
Multiplicity
Example:
O
3
O
3 : 2: 3
1 Singlet
1 Quartet
1 Triplet
O
OH
O
OH
O
3
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
3. The natural product (+) discodermolide (shown below) was first isolated from a marine sponge
in 1990. Early studies showed promising activity against chemotherapy-resistant lung cancer cells
as well as synergistic activity with paclitaxel, a frequently employed cancer therapeutic. In 1993
the first total synthesis of discodermolide was published and in 2004 Novartis attempted the first
industrial scale synthesis with over 30 steps to obtain enough material for clinical trials.
H
O
OH
O
OH
O
OH
NH 2
O
OH
a) Identify the circled stereo centers in discodermolide (depicted above) as either R or S using
the Cahn-Ingold-Prelog convention. Write your answers next to the corresponding circles on the
molecule above.
b) Identify each double bond as either E or Z and denote it accordingly on the molecule above.
c) Convert the depiction of meso-butane-2,3-diol to the right into
H3C
a Newman projection by filling in the back carbon “C3” in box A.
CH3
C2
C3
Then complete the Newman projection that are produced by a 60°
HO
clockwise rotation of the back carbon “C3” in the boxes B-F.
CH3
meso- butane-2,3-diol
CH3
CH3
60° clockwise
60° clockwise
H
OH
H
OH
A
H
OH
B
C
60° clockwise
60° clockwise
CH3
CH3
CH3
60° clockwise
60° clockwise
H
OH
OH
H
F
OH
H
E
OH
D
4
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
4. Altrose (depicted to the right) is a diastereomer of glucose. It is an unnatural
HO
sugar that cannot be metabolized by most organisms. However, it is
metabolized by some strains of the bacterium Butyrivibrio fibrisolvens. HO
O
Producing a food source that can only be processed by your species is a great
competitive advantage on the micro-biome scale.
HO
OH
OH
Altrose
a) Show the 3D structure of altrose by filling in the two cyclohexane chair
frameworks below (note the position of the oxygen atom has already been fixed!).
O
O
HO
b) Which of the two chair conformers from part a) is more stable? Circle it!
HO
c) Under acid catalysis, the hexose ring can be opened to the straight chain
O
HO
form. The overall reaction is shown to the right.
OH
OH
Complete the Fischer projection for the straight chain form of altrose!
H3O+
OH OH
CHO
O
OH
OH OH
CH2OH
5
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
5. For each set below circle the most stable carbocation.
H
H
H
H3C
H
H
H
H3C
CH3
CH3
H3C
CH3
a)
b)
CH3
c)
H3C
CH3
CF3
F3C
CCl3
CF3
Cl3C
CBr3
CCl3
Br3C
CBr3
d)
e) From the set below, circle the solvent that is expected to stabilize a carbocation the best.
F F F F
O
F
H2 N
H
F
F
F
F
F
F F F F
6
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
6. Complete the following reactions by showing the structure(s) of the major product(s). If a
racemic mixture of product is created, write “racemic” under your product.
Br2
a)
H 2O
CH3ONa
b)
+
MeOH
CH3ONa
c)
MeOH
Cl
1) O3
2) (CH3)2S
d)
O
O
O
O
e)
O
7
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
7. For each of the reactions shown below fill in the reagents that will enable the transformation and then
circle then appropriate mechanism out of the five available options (SN1, SN2, E1, E2, radical).
a)
Br
SN1 / SN2 / E1 / E2 / Radical
b)
O
Br
SN1 / SN2 / E1 / E2 / Radical
c)
Br
SN1 / SN2 / E1 / E2 / Radical
d)
O
I
O
SN1 / SN2 / E1 / E2 / Radical
8
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
8. Please write out initiation and propagation steps as well as at least one possible termination
step for the following radical chain reaction:
Br
NBS
light
racemic
Initiation step(s):
Propagation step(s):
Termination step (at least one):
9
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
9. Provide a synthetic procedure to transform the given starting materials to the desired products.
Indicate all reagents used along the way and draw out all intermediate products that you need to
prepare along the way. You don’t have to provide mechanisms for any of the transformations, just
indicate all reagents used and all carbon-containing products that are formed.
a)
???
O
O
10
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
b) HINT: If you are having trouble introducing the terminal alkene, try synthesizing it at an early
step in your route and then bring it along into the C-C Bond formation step.
OH
???
11
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
New Material: Organometallics
1. Fill in the boxes with the appropriate reagent(s) or product(s) for the following reactions.
Indicate stereochemistry where applicable.
a)
Br
Mg0
THF
b)
MgBr
1. CO2
2. dilute HCl
c)
OH
MgCl
d)
O
1.
H
MgCl
2. Dilute HCl
e)
O
Li
12
Organic Chemistry 2: Sessler CH328N
Homework Set 1
Due Thursday, January 30, 2020
2. Draw the arrow-pushing mechanism for the following reaction
OH
O
1.
Li
OH
+
O
2. dilute HCl (H3O+)
13