Download 1 1. (5 pts. each, 50 pts. total) Draw the major product of each of the

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1. (5 pts. each, 50 pts. total) Draw the major product of each of the following
reactions. Assume aqueous workup in all cases (that is, draw neutral products). Do
not draw mechanisms!
(a)
CN
Ph
LDA; PhCH2Br
CN
(b)
O
O
O
O
OEt
NaOEt
EtO
OEt
(c)
CO2H
CO2Et
EtOH
cat. H2SO4
Ph
Ph
(d)
excess NaOH
CN
CO2H
CO2H
CN
(e)
OMe
O2
OMe
OOH
2
(f)
O
NH2
CN
SOCl2
(g)
O
H
MeNH2
NHMe
H2, Pd/C
(h)
O2N
Br2
O2N
Br
FeBr3
(i)
O
O
O
LDA
O
N
Ph
O
(j)
OH
LiAlH4
OH
O
CH3
CO2Et
O
N
Ph
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2. (20 pts. each, 60 pts. total) Design syntheses of the two compounds below from
the indicated starting materials. Both syntheses will require two or more steps.
Show each intermediate compound and all reagents you will need for each step.
(Don’t panic if you can’t remember the reagents for a particular step; partial credit
will be given.) Do not show mechanisms.
(a)
O
O
OEt
one or more alcohols
Retrosynthesis:
O
O
O
2
OEt
OEt
OH
Forward:
O
CrO3
EtOH,
OH
OH
H2SO4
O
O
O
NaOEt
OEt
OEt
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(b)
H2N
O
benzene
O
Retrosynthesis:
O
H2N
H2N
O
O
O
O
O2N
Forward:
O
O
Ac2O
HNO3
O2N
SnCl2
AlCl3
O
H2N
mCPBA
H2N
O
O
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(c)
O
OEt
OH
Retrosynthesis:
O
O
OEt
OEt
CO2Et
O
OEt
+
Br
CO2Et
OH
Forward:
EtO2CCH2CO2Et
PBr3
OH
Br
CO2H
CO2H
∆
CO2Et
NaOH
NaOEt
CO2Et
CO2H
EtOH
H2SO4
CO2Et
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3. (45 pts. total) Draw reasonable mechanisms for each of the following reactions.
(a) (10 pts.)
O
OH
O
cat. H+
See exam 3.
O
+
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(b) (15 pts.)
O
O
CH3MgBr
Br
OEt
O
BrMg
Br
O CH3
CH3
OEt
Br
OEt
O
BrMg
Br
CH3
CH3
CH3
O
O CH3
CH3
Br
CH3
CH3
CH3
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(c) (20 pts.)
O
CH3CN
OH
OH
N
H
H2SO4
H+
CH3
N C
OH2
H
N C
CH3
OH2
O H
N C
CH3
H+
H
O
N C
H
O
CH3
N C
H
CH3
CH3
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4. (5 pts. each, 20 pts. total) When the Friedel–Crafts reaction shown below is carried
out, four ketones are obtained. Two of the products contain the phenol (aromatic
alcohol) functional group and the two others contain the ester functional group.
HO
Ac2O
A +B+C + D
AlCl3
(a) What spectroscopic technique would allow you to distinguish the two ester
products from the two phenol products? Be specific about how the technique would
allow you to distinguish them.
IR: presence or absence of carbonyl stretch
NMR: presence or absence of C=O or CH3
(b) Draw the two products that contain the phenol functional group.
O
HO
HO
O
(c) On the next page is a 1H NMR spectrum of one of the phenol products. Circle the
compound you drew in (a) which would give rise to this 1H NMR spectrum.
The para product
(d) What 1H NMR feature would distinguish the other phenol product from the
one you circled?
The other phenol product would have four different resonances for the aromatic
H’s.
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5. (5 pts. each, 25 pts. total) Answer each of the following questions.
(a) Why do Claisen condensations such as the one below require a full equivalent of
base such as NaOEt to proceed to completion?
O
EtO
O
NaOEt
CH3
O
EtO
CH3
Because the product is very acidic and consumes the basic catalyst.
(b) Why doesn’t the following reaction work as written?
O
Ph
O
O
LiAlH4
OEt
Ph
OH
Because ketones are reduced with LiAlH4, too. The product is a diol.
(c) Why is F is an ortho–para director in Friedel–Crafts reactions, even though it is
the most electronegative element?
It has lone pairs that can stabilize a neighboring + charge by resonance.
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(d) Why doesn’t the following reaction work as written?
MeNH2 + PhCH2Br
MeNHCH2Ph
Multiple alkylations of the N occur.
(e) How many resonances will you see in the 1H NMR spectrum of the following
compound?
CN
Five. The two H’s of the CH2 group are diastereotopic.