Initials______________
Chemistry 634, Fall 2011
Final Exam
Prof. Donald Watson
300 points (3 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: ________/25
Question 2: ________/23
Question 3: ________/32
Question 4: ________/20
Question 5: ________/40
Question 6: ________/40
Question 7: ________/40
Question 8: ________/40
Question 9: ________/40
_____________________
Total:_______/300
Page 1/12
Initials______________
1) (25 points, 5 points each) 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) TsNHNH2
2) NaBD3CN, TsOH
O
t-Bu
O
O
O
Et
N
1) LDA, then MeI
2) NaBH4
Bn
O
Ph
Li(sBu)3BH
Me
Me
H
O
iPrMgBr
H
V(O)(acac)2, tBuOOH
Bu
OH
_______/25 points
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Initials______________
2) (23 points) In the spaces below, provide the missing reagents and intermediates
needed to complete the synthesis. Note: More than one step or reagent may be
required over each arrow.
TBDPSO
1) O3, then DMS
2) BuLi,1, 0 °C
8 pt
O
O
OBn PPh3 Br
Me
Ph
7 pt
1
Me
Me
O
Me
N
O
O
Me
NH2
O
O
8 pt
O
OH
Me
Me
Me
O
_____/23 points
3) (32 points) In the spaces below, provide the missing reagents and intermediates
needed to complete the synthesis. Note: More than one step or reagent may be
required over each arrow.
Ph
O
O
O
8 pt
OH O
Me
OH O
Me
Me
Me
OEt
8 pt
OMOM
Me Me
HO
OH O
Me
Me
Me
O
F3C
OH
, Et3SiH
Me
Me
OH O
Me
OMOM
8 pt
OMOM
3
2
Cl
O
OH
Cl
Cl
DMAP, 125 °C
Et
MOMO
O
O
O
8 pt
O
O
Me
Me
Et
O
Me
Me
OMOM
______/32 points
Page 3/12
Initials______________
4) (20 Points) Referring to the Scheme shown in Question 3, in the space below, please
provide a detailed mechanism for the conversion of 2 to 3, and rationalize the observed
stereochemistry.
______/20 points
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Initials______________
5) (40 points) In the space below, please provide a detailed mechanism for the reaction
shown that accounts both for the connectivity and stereochemistry of the product.
1) Bu2BOTf, iPr2NEt
2) PhCHO
O
Ph
Me
O
OH
Ph
Ph
Me
______/40 points
Page 5/12
Initials______________
6) (40 Points) A) Please provide a mechanism for the transformation shown below. For
now, you can ignore stereochemistry.
NP(S)Ph2
Br
Br
Me2S
OEt
Br
NHP(S)Ph2
O
O
OH
K2CO3
CO2Et
90%, dr = 96:4
20 pts
B) Using Newman Projections, in the space below please provide a reasonable model
to account for the stereoselectivity in the transformation shown in question 6a.
20 pts
______/40 points
Page 6/12
Initials______________
7) (40 Points) A) Please provide a complete mechanism for the transformation shown
below. For now, you can ignore stereochemistry.
Ph
OH
Me
O
OEt
1) PhCHO, tBuOK, 0 °C, 3h
2) DIBAL, then H3O+
O
Me
O
O
H
20 pts
B) In the space below please provide a reasonable model to account for the
stereoselectivity in the transformation shown in question 7a.
20 pts
______/40 points
Page 7/12
Initials______________
8) (40 points) Using a maximum of 5 steps, propose a synthesis of 5 using the given
starting material 4 and any other commercial or readily accessible reagents.
O
O
Ph
4
Ph
Me
5
______/40 points
Page 8/12
Initials______________
9) (40 points) Using a maximum of 5 steps, propose a synthesis of 7 using the given
starting material 6 and any other commercial or readily accessible reagents.
Me
N
NH2
I
6
O
7
CO2Me
______/40 points
Page 9/12
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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Initials______________
This page provided for scratch paper. No answers on this paper will be graded.
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