mit-o2-h3
-
Upload
vinh-hoang -
Category
Documents
-
view
213 -
download
0
Transcript of mit-o2-h3
-
8/16/2019 mit-o2-h3
1/10
Massachusetts Institute of Technology 5.13, Fall 2006
Dr. Kimberly L. Berkowski Organic chemistry II
EXAM 3 EXTRA PROBLEMS
What to expect on Exam #3:
1.
~1 Labeling experiment2.
~2 Mechanisms
3.
~2 Syntheses
4. ~5 Transformations – supply missing product
5.
~5 Transformations – supply missing reagents
6.
~3 General question
-
8/16/2019 mit-o2-h3
2/10
1.
(4 points each, 8 points total) In the boxes, please provide the reagents for the
illustrated transformations. More than one step may be required.
2. (2 points each, 8 points total) Please provide the products of the following reactions. If
no reaction is expected, write “NR”.
Name_____________________1
O
OHi-Pr
O
Hi-Pr
O
OHi-Pr
i-Pr Br
(a)
(b)
Figure by MIT OCW.
Et Cl
O
Et OH
O
Et OMe
O
(a)
(b)
(c)
(d)
Et NMe2
O
1. Excess Na BH4
2. Workup
2. Workup
1. Excess MeMgBr
2. Workup
1. Excess MeLi
2. Workup
1. Excess LiAlH4
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
3/10
3. (2 points each, 16 points total) Please provide the requested products or reagents. If no
reaction is expected, write “NR”.
Name___________________
2
NH2 N2 Br
(d)
(c)
NH2
O
O
n-BuH2O
H3O+
Me Me
H2 N
cat. H+
(b)1. LiAlH4
2. workup
Me
MeMe
Me NH2 NH2
H2O2, ∆
(a)
O
n-Bu
CN
OH
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
4/10
4. (11 points) Provide a detailed mechanism for the illustrated conversion of acetic acid
(A) to acetyl chloride (B).
OHMe
O
ClMe
OO
+S
Cl Cl
+ +SO2 HCl
BA
Name___________________
3
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
5/10
5. (11 points each, 22 points total) Please provide syntheses for only two of the three
indicated compounds. All the carbon atoms should be derived from the allowed starting
materials. You may use any common reagents.
Name___________________
4
Allowed Starting Materials:
Me
MeMe Me
Me
Me CO2OH OH
Me
Me
C N
Me
Me
HO
MeMe NHPick Two:
Synthesis # 1:
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
6/10
5. (Continued)
Name_______________________
5
Allowed Starting Materials:
Me
Me
Me
Me Me
Me
Me Me
CO2 OH
Me
Me-OH
Me
Me
C N
HO
NH
Pick Two:
Synthesis #2:
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
7/10
6. (11 points) Provide a synthesis that will selectively convert A to B. Show all the key
intermediates and furnish all the important reagents. This is not a one-step process.
Me
O
Me
O
A
HO
B
Name_____________________
6
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
8/10
7. Methyl acetimidate (A) is hydrolyzed in aqueous sodium hydroxide to give mainly
acetamide and methanol (eq 1). In aqueous acid, A hydrolyzes to give primarily
methyl acetate and ammonium ion (eq 2).
a) Provide a detailed mechanism for the illustrated process. Please show all arrow
pushing.
b) Provide a detailed mechanism for the illustrated process. Please show all arrow
pushing.
c) Briefly explain why the two reactions provide different products.
7
OMe NH2MeA
H2O
NH
Me
O+ (1) MeOH
HO-
Figure by MIT OCW.
OMe OMeMeA
H2O
NH
Me
O
NH4+ (2)excess H
+
Figure by MIT OCW.
-
8/16/2019 mit-o2-h3
9/10
8. Synthesize the indicated compounds from the allowed starting materials shown
below. All of the carbons of the target compounds should be derived from the
allowed starting materials.
9.
Provide the best stepwise mechanism for the illustrated process. Please show all
arrow pushing.
10. (a) Provide the best mechanism. Please show all arrow pushing.
(b) Provide the best mechanism. Please show all arrow pushing.
MeOH
MeMeMe
Me
Me
MeMe
Me
Me OH CO2 ethylene CNO
O
O
O
H
H
H
H
N
N
N
Br
Br Br
NH2
Allowed starting materials
(b)
(c) (d)
(e)
Figure by MIT OCW.
+
NH2
H
NaBH3CN
N
OO
H H
Figure by MIT O
+
Me
H
N=C-Me N
Figure by MIT O
+
NH2 N
Me
OH
H
H2O
Figure by MIT OC
-
8/16/2019 mit-o2-h3
10/10
11. Consider the labeling experiments outlined below:
Stop each reaction at 50% convers
and examine the recovered startin
material for incorporation of Ø
Under acidic hydrolysis conditions, would you expect more Ø incorporation into the
amide (eq 1) or the ester (eq 2)? Your answer should include the mechanism for
these reactions.
9
HO
Me NHMe
+, H2φ
HO
Me OMe
+, H2φ
(1)
(2)
Figure by MIT OCW.