Chem 242
Spring 2008
Problem Set 7
Question 1. Give the IUPAC name for each of the following compounds.
CHO
O
Me
Me
Me
Me
3-methyl-2-butanone
3-methyl cyclopentanecarboxaldehyde
CH3
O
O
Me
Cl
Me
H
Me
Cl
4,5-dichlorohexanal
O
6-methyl-2,3-octanedione
Question 2. Provide reagents to most efficiently perform the following transformations.
Ph
O
N
aniline
a)
H
CH3
(removal of H2O)
H
CH3
OH
b)
1. Hg(OAc)2, H2O
H3C
2. EtMgBr
H3C
H
CH3
Me
OH
c)
1. Hg(OAc)2, H2O
H3C
Me
2. NaBH4
H3C
CH3
Me
O
OH
d)
1. O3 (any workup)
2. KCN/HCN
3. H3O+
NH2
Chem 242
Spring 2008
Question 3. A CH242 student wanted to perform the following reaction for their
laboratory synthesis project:
OH
O
O
BrMg
H
O
H
H
H
(followed by an H+ workup)
A
Why will this transformation fail? How might you make compound A from
benzaldehyde?
O
BrMg
H
These functionality are incompatible
(they will react with each other)
O
MeO
H
BrMg
OMe
OH MeO
H
H
H
OH
OMe
O
H3O+
H
H
A
Chem 242
Spring 2008
Question 4. Provide a mechanism for the following transformation.
O
O
NaBH4
Me
Br
Me
H
O
H
Na
B
H
Na
O
H
Br
Br
Me
Me
H
O
Me
An SN2 reaction!
O
Br
Me
Chem 242
Spring 2008
Question 5. Provide appropriate reagents to perform the following transformations.
Hint: Think backwards!
Hint for (c): How can we make secondary alcohols?
O
1.
OMe
Cl
, AlCl3
Me
2. MeLi
3. MeI (before workup of step 2)
HO
O
1.
Me
Cl
, AlCl3
Me
Me
2. (Ph)3P
Me
CH2
3. BH3; then HOOH, –OH
(hydroboration & oxidation)
Instead of:
Na
OH
O
H+ workup
Me
Me
React the alkoxide with a different electrophile:
Na
O
Me
Me
I
OMe
Me
Chem 242
Spring 2008
CO2Me
1.
Me
, heat
Me
HO
c)
OH
2. O3, reductive workup
3. MeMgCl (+ workup)
CO2Me
Question 6. Provide a mechanism for the transformation shown below.
Me
Me
O
Me
HO
H+ catalyst
OH
O
O
Me
Me
Me
OH
Me
OH
O
H+
O
H
O
HO
O
Me
Me
Me
H+
Me
Me
OH
O
Me
OH
OH
H
O
H2O
H
OH2
H
O
O
HO
Me
Me
Me
H2O
Chem 242
Spring 2008
Question 7. Provide a mechanism for the transformation shown below.
Me
H+
O
Me
O
Me
O
O
H2O
Me
Me
Me
OH
OH
H
Me
O
Me
Me
Me
Me
H
Me
Me
H
O
H
Me
H2O
H
H+
Me
H
Me
OH
Me
H
O
Me
H
Me
O
H
H2O
Me
Me
Chem 242
Spring 2008
Question 8. The following reaction produces two products with the molecular formulas
shown below. Provide a mechanism for the formation of each product. Assume an acid
workup is performed.
O
Br
NaBH4
Two products:
C6H10O and C6H11OBr
"H–"
H
O
Br
axial attack
Br O
Br
SN 2
H
H
H
O
H
"H–"
O
H
C6H10O
equatorial
attack
O
OH
Br
O
Br H
H
H
epoxide formation not possible
H
workup
Br H
H
C6H11OBr