Initials______________
Chemistry 634, Fall 2009
Final Exam
400 points (3 hours)
Prof. D. Watson
•
•
•
You may use model sets and hand-written note cards or note sheets. No
other notes or aids are allowed.
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.
Points will only be awarded for clearly communicated answers.
Name _______________________________________
Question 1: ________/100
Question 2: ________/100
Question 3: ________/25
Question 4: ________/25
Question 5: ________/50
Question 6: ________/50
Question 7: ________/50
_____________________
Total:_______/400
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Initials______________
1) (100 points) Predict the expected major product for each reaction sequence.
Pay attention to stereochemistry and denote it where needed.
OH
OEt
OEt
H3C
OEt
+
OH
150 °C
cat H+
Chem Lett 1974, 3, 741
20 pts
C6H8O2
SiMe3
O
BF3•Et2O
OAc
77%
dr = 94:6
Me
JACS, 2003, 125, 15521
20 pts
C9H16O
1) O3, then PPh3
2) (PhO)2P(O)CH2CO2Et, NaH
OTBS
BnO
73% overall
dr ca 5:1
Org. Lett, 2009, 11, 5274
20 pts
C21H34O4Si
O
O
1) Bu2BOTf, Et3N; 1
2) MeAl3, (MeO)NHMe
3) TMSCl, imid
O
Me
N
O
Ph
OAc
H
Me
JACS 2002, 124, 4552
O
H
C16H30NO4Si
Me
CH2I2, Et2Zn
O
H
MeO
20 pts
1
92%
O
Me
single isomer
JACS 1995, 117, 1455
20 pts
C18H28O4
____/100 points
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2) (100 points total) Provide the necessary reagent(s) to provide high yielding
transformations. Write answers in box provided. Be mindful of stereochemistry, if
specified. Note, for each scheme more than one step may be required. If more
than one step is proposed, please indicate clearly.
TIPSO H
TIPSO H
Me
H
20 pts
NBoc
O
Me
H
Org. Lett. 2009, 11, 5554
NBoc
TIPSO H
O
O
TIPSO
Me
Me
H
20 pts
NBoc
H
Org. Lett. 2009, 11, 5554
NBoc
20 pts
BnO
BnO
OH
H
Org. Lett. 2009, 11, 5275
O
OH
H
OH
OH
H
O
Bu
Me
20 pts
racemic
N
JOC 1994, 59, 5841
Me
Bu
ignore stereochemistry
OH
Me
O
OH
Me
Me
Me
20 pts
JACS, 1988, 110, 3560
Me
OH
Me
Me
Me
______/100 points
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3) (25 points) Curran has demonstrated the following reaction (J. Chem. Soc,
Perkins Trans 1, 1994, 1377). In the space below, provide a complete
mechanism that accounts for this transformation. Do not concern yourself with
the stereochemistry.
O
MeO
Br
AIBN, Bu3SnH
N
CO2Me
O
O
N
Bn
Ph
______/25 points
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Initials______________
4) (25 points) Nokami has recently shown (ACIE, 2003, 42, 1273) that
of aldehydes with the chiral alcohol 2 results in the formation
enantioenriched homo-allyl alcohols (as shown). In the space below,
detailed mechanism for this transformation that explains both product
and the stereoselectivity observed in the reaction.
treatment
of highly
provide a
formation
Me
iPr
CHO
2
Me
OH
OH
2 equiv.
10 mol% TsOH•H2O
CH2Cl2, rt, 20 h
TsOH =
Me
Me
83%, 99% ee
SO2OH
______/25 points
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5) (50 points) During his seminar at Organic Journal Club on Thursday, Dec. 10th,
Prof. MacKay presented an efficient route for the preparation of 3. In the space
below, either show how he prepared the compound or propose your own
synthesis starting from simple, readily available starting materials.
O
EtO
Me
OEt
Me
3
O
______/50 points
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Initials______________
6) (50 points) In the space below, propose a racemic synthesis of 4 using the
given starting material.
O
MeO2C
O
4
H
JACS, 1977, 99, 6066
O
H
I
______/50 points
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7) (50 points) In the space below, propose an enantioselective synthesis of 5
using the given starting material.
O
HO
OH
Org. Lett. 2009, 11, 5383
MeO
5
Me
______/50 points
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