exam3v3

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CHM 223
Exam 3
12/8/2017
Name:______________________________
Honor Code:
Please read each question carefully.
Problems 1-7 are worth 5 points each.
1.The reaction below will not work as written because:
1. NaNH2/NH3
HO
2.
Br
HO
a) The starting material has cis stereochemistry and is too sterically hindered too react
b) Allyl bromide used in the second step is not a reactive electrophile
c) The starting material has a hydroxyl group, which will consume NaNH2 in an acid-base
reaction
d) The triple bond of the starting material will simply get reduced to a double bond in the first
step of the reaction
2. Which of the following would NOT give 1-bromo-1-methylcyclohexane as the major product?
a)
c)
HBr
ROOR
Br2
HBr
b)
d)
OH
UV light
3. (Z)-3-methyl-2-pentene reacts with Br2/H2O. The product is:
1
H2SO4
NaBr
4. Which of the sequences shown can be used to accomplish the following transformation?
?
Br
O
a) H2SO4/heat, then MCPBA
b) NaOCH3/MeOH, then Br2/H2O, then NaOH/H2O
c) NaOCH3/MeOH, then Br2/H2O, then H2SO4
d) H2SO4/heat, then Br2/H2O, then NaOH/H2O
5. (3S,4R)-3,4-Dimethylcyclopentene is treated with ozone followed by dimethyl sulfide to give a
single product. Which one?
1. O3
2. DMS
a)
H
H
O
b)
H
O
H
O
c)
O
H
H
O
d)
O
H
H
O
6. Select the best reaction sequence to make the following ketone.
a) 1. Propyne, NaNH2
b) 1. Acetylene, NaNH2
c) 1. 1-hexyne, NaNH2
d) 1. 1-pentyne, NaNH2
2. 1-bromobutane
2. 1-bromopentane
2. bromomethane
2. bromoethane
3. H2O, cat. HgSO4, H2SO4
3. H2O, cat. HgSO4, H2SO4
3. H2O, cat. HgSO4, H2SO4
3. H2O, cat. HgSO4, H2SO4
7. Which sequence of reactions would work best in converting cycloheptene to 1,3cycloheptadiene?
a) 1. NBS/heat
b) 1. NBS/heat
c) 1. Br2/H2O
d) 1. NBS/heat
2. t-BuOK/t-BuOK, heat
2. Hg(OAc)2/H2O, then NaBH4
2. H2SO4, heat, then NBS/heat
2. H2O
8. The following reaction sequences have missing reagents, products or reactants. Fill in the
missing information in each case. Pay attention to stereochemistry where necessary. (59
points).
a)
b)
1. BH3*THF
2. H2O2/HO–
Br2/hν
(two products)
2
O
2 eq. HBr
c)
Br2
d)
CCl4
OH
C8H15BrO
O
1. O3
e)
2. H2O
(only product)
Br
Br2
f)
ethanol
g)
OH
O
cat. OsO4
NMO
Br
9. Use the “curved arrow formalism” and draw a detailed, stepwise a mechanism for the
following reaction:
conc. H2SO4
OH
Δ
3
10. Design synthetic routes to each of the following compounds from the indicated
starting materials and any other necessary reagents. Note that the target molecule is
shown on the left and starting material on the right in each case. (40 points)
a)
I
from
b)
SCH2CH3
from
c)
Br
OH
from
H
OH
d)
OH
from
OH
4
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