Initials______________
Chemistry 634, Fall 2012
Midterm Exam
Prof. Donald Watson
260 points (2 hours)
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Closed note, closed book. No calculators allowed. You may use a molecular
model set.
Answers should be written in boxes provided. Other markings will not be
considered. Scratch paper can be found at the back of the exam packet.
Please initial each page at the top.
Points will only be awarded for clearly communicated answers.
Please make sure you have all pages of the exam packet (12 pages).
Name _______________________________________
Question 1: ________/50
Question 2: ________/50
Question 3: ________/30
Question 4: ________/30
Question 5: ________/30
Question 6: ________/30
Question 7: ________/40
_____________________
Total:_______/260
Page 1/12
Initials______________
1) (50 points) Predict the expected major product for each reaction sequence after
aqueous work-up, drawing your answer in box provided. Denote stereochemistry where
needed. If no reaction is expected, state so.
1) Me3Al, HN(Me)(OMe)
2)
Li
Me
OMe
OMe
O
1) MgSO4, H2N
O
Me
O
S
Me
Me
Me
Me
Me
2) PhLi
3) HCl, H2O
Li, NH3;
then Et-I
H
O
O
cat.
O
NH HN
PPh2 Ph2P
HO
OH
cat. Pd2(dba)3
Ts
excess
N C O
C14H15NO4S
O
OEt
1) HCl, H2O, heat
2) CH2N2
_______/50 points
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Initials______________
2) (50 points) Please provide the reagents needed to carry out each of the following
transformations. Note, in each case, more than one step may be required.
Me
O
Br
Br
NH2
I
Me
OTBS
H
OTBS
Me
H
Me
OTBS
H
O
OTBS
O
N
N
Ph
O
H
MeO
MeO
O
O
O
O
OH
OAc
CN
OMe
N
H
HH
OH
OAc
CN
OMe
H
H
O
H
N
Me
CO2H
H
N
H
HH
N
Me
_______/50 points
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Initials______________
3) (30 points) Please provide the oxidation state and d-electron count for each of the
following complexes.
Me
OsO4
Mo
O
O
O
Ph
Ph
Cl
P
Ru
P Cl
Ph
Ph
CoCl3
Zr(NMe2)4
H H
N
N
H H
SiMe3
Pd
SiMe3
_____/30 points
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Initials______________
4) (30 points, 3 points each) Complete the following equilibria, showing all products.
Using your knowledge of pka’s, predict the and equilibrium constant for each reaction.
In all cases, please draw the expected product, even if the reaction is highly
endothermic.
Me
Me
iPr
2NH
N Li
Me
O
tBuO
Me
Keq =
N
H
H
H
Keq =
HCl
O
Me
ONa
Keq =
EtONa
Ph
H
Keq =
LDA
CH3
Keq =
______/30 points
Page 5/12
Initials______________
5) (30 points) Provide a model that rationalizes the following selectivity.
O
O
Me
LDA
THF/HMPA
O
Me
+
O
OLi
Me
OLi
91
:
9
______/30 points
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Initials______________
6) (30 points) Please provide a detailed mechanism for the following reaction.
O
MeO
MeO
O
O
N
HO
Me
Al(OiPr)
N
3
O
Me
65%
______/30 points
Page 7/12
Initials______________
7) (40 points) Starting with 1 and using 13C-DMF as your only source of isotopically
enriched starting material, please propose a synthesis of isotopically labeled 2.
O
+
O
CONEt2
OH
1
O
13C
H NMe2
13C-DMF
13C
O
O
CONEt2
OH
2
______/40 points
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Initials______________
This page provided for scratch paper. No answers on this paper will be graded.
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Initials______________
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Initials______________
This page provided for scratch paper. No answers on this paper will be graded.
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Initials______________
This page provided for scratch paper. No answers on this paper will be graded.
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