CHM238 Spring 2002
April 12, 2002
Exam 3
Name
1. (8 pts) Naming. You know the drill. Come up with the correct name for the following.
CH3
O
O
O
CH3
CH2
O
CH3
H3C
CH2
CH2
OH
H
O
CH3
C
H
2. (13 points) Mechanism Provide lone pairs and electron pushing arrows to complete the
following mechanism. Then answer the questions,
H
+
OH
OH2
H
Ca
O
O
+
Cb
OH
Ca
H2O
H2O
Cb
+
OH
OH
H
H3O
This is syn or anti addition?
The water attacks the carbon labeled Cb of the expoxide. Would the product be the same if the
water attacked from the Ca carbon? Explain.
The H3O+ generated in the reaction during the last step can go back and react with another
cyclohexene oxide. What is the role of H3O+ in this reaction?
Why must the cyclohexene oxide be protonated with acid, before this reaction can occur?
How would you synthesize cyclohexene oxide?
3. (6 points) Which epoxide would work to complete the following reaction sequences:
CH2 CH3
HO
+
MgBr
H3C
H3C C
H3C
CH2
CH2
H
O
H3C
O
H3C
Dilute Acid
+
H3C OH
H3C
CH
CH2
CH2
OH
+
CH
CH2
CH2
O
CH3
+
4. (7 points) In the Williamson ether synthesis, here are two reaction sequences to make benzyl
tertbutyl ether.
CH3
Na
O
OH
-
A
H3C
ether
Br
CH3
CH3
CH3
Na
B
H3C
H3C
OH
O
Br
-
ether
CH3
CH3
Which reaction sequence is the best? Explain.
What would be the main organic product of the wrong reaction sequence?
Draw the ether that would be synthesized.
5. (12 pts) Which ketone or aldehyde would work to complete the following sequences?
+
+
HO
OH
H
O
O
O
H3C
O
+
H
+ H2N
CH3
OH
N
OH
CH3
OH-
+ H2N
NH2
Heat
OH-
+
OH
Ag2O
Heat
H2C
O
CH3
6. (24 pts) The reaction of the following with the organometallic reagents (either a Grignard or
R2CuLi) will produce the products shown below.
(a) The same Grignard, RMgBr, reacts with 4 different compounds to make the following products.
Provide a structure for each compound. Then, provide a structure for R.
O
OH
followed by acid wu
OH
followed by acid wu
CH3
CH3
R
MgBr
+
OH
followed by acid wu
CH3
OH
followed by acid wu
R=
(b) The same Gillman reagent, R2CuLi, reacts with 2 different compounds to make the following
products. Provide a structure for each compound. Then, provide a structure for R
O
followed by acid wu
CH3
R2CuLi
+
followed by acid wu
CH3
O
R=
7. (4 pts) Provide a Wittig reagent and ketone or aldehyde that would make this alkene:
8. (10 pts) Starting with whatever is given and any other organic or inorganic reagents, come up
with a reaction sequence to make the following. More than one step will be required. Choose 2 out
of 3 and cross out one or graded in order.
O
(a)
OH
H3C
OH
(b)
CH3
OH
O
(c)
9. (8 pts) Provide the reagents for the sequences below:
OH
OH
CH2
O
+
+
A
+
B
H
A=
B=
C=
D=
C
+
O
D
10. (12 pts) Give an example of that satisfies the following conditions. There may be more than
one right answer. Draw correct structures with the right number of bonds and correct charges.
Choose 4 of 5 and cross one out or graded in order.
(a) Any cyclic hemiacetal:
(b) The alkyl bromide that was reacted with Ph3P:, followed by deprotonation with n-BuLi that
made the Wittig reagent you provide here:
(c) Match the acids below with the most appropriate pKa’s: 0.7, 4.2, 15.5
O
O
OH
S
OH
O
methanol
(d) An alkyne that will react with [(1) BH3 (2) basic hydrogen peroxide solution] to make butanal.
(e) The reagents necessary to turn ethyl bromide into propanoic acid.