Name _______________________
Page 1
Reaction
analysis:
provide
the
requested
information
in
each of the following chemical
A.
transformations. Show all missing starting materials and products unless otherwise
indicated, and if any reaction results in a stereoisomeric mixture, draw one and indicate "+
enantiomer," "+ diastereomer," or "+ more than one stereoisomer" in the box.
I. (30 points)
(a)
(i) C12H16
(ii) The product shown forms with (circle
the best answer):
KMnO4
no other stereoisomers
HO
its enantiomer
OH
its diastereomer
H
with > 2 other stereoisomers
3
2
(ii) Major regioisomer only
(i)
(b)
H
HO
H
1) BH3
HO
O
O
O
HCl
Cl
Cl
2) H2O2/NaOH
O
O
+ enantiomer
either one may be drawn
4
+ enantiomer
either one may be drawn
4
(c) (i)
(ii) Draw the organic products with the info given:
2 equiv
1H-NMR: 1 peak
NH3
1) O3
Na
2) (CH3)2S
O
O
H C
1 equiv
1H-NMR: 2 peaks
O
C
H
H3C
1 equiv
1H-NMR: 1 peak
C
H
O
O
C C
H
H
6
3
(d)
(ii)
(i)
OR
O
right C does not have to be 3D
O
O
OR
O
draw one and "+ enantiomer"
4
O
H
H2
Pt
draw one and "+ enantiomer
4
Name _______________________
Page 2
II. (26 points)
In the following reactions, an optically pure starting material is transformed using slightly
different reagents and/or conditions. Predict the product(s) for each transformation, using
the information given. Then consider how the changes might affect the rate of that same
reaction path.
(i) an optically inactive mixture containing two
chiral compounds: C7H14OS;
draw each
(a)
O
Cl
CH3S
Na
O
CH3CH2OH
O
(R)
(S)
SCH3
SCH3
1
4
assuming that the same reaction mechanism occurs (with identical or analogous product(s) forming)...
(ii) if 1 was changed to
Cl
(iv) if
the reaction rate would
(circle the best answer):
increase
decrease
remain the same
CH3S
the reaction rate would
(circle the best answer):
Na
was doubled in
concentration
increase
decrease
remain the same
3
(iii) if 1 was changed to
O
3
(v) if
Br the reaction rate would
(circle the best answer):
the reaction rate would
(circle the best answer):
CH3CH2OH
was changed to
increase
decrease
remain the same
CH2Cl2
increase
decrease
remain the same
3
3
(i) a single chiral product: C7H11NO
(b)
O
Cl
H
2
O
CN
NaCN
CH3CH2OH
H
4
(ii) if
CH3CH2OH
was changed to
CH2Cl2
the reaction rate would
(circle the best answer):
increase
decrease
remain the same
(iii) if
NaCN
the reaction rate would
(circle the best answer):
was doubled in
concentration
3
increase
decrease
remain the same
3
Name _______________________
Page 3
A. DBN is a strong, bulky base that is often used to encourage elimination reactions over
substitution reactions. In both of the following cases, the resulting bimolecular elimination
reaction yields a single major product which can be explained by conformational favorability
in the starting material. Draw the product for each and draw the conformation that favors its
formation.
(i) Using a chair, draw the conformation
(ii) Selected product
that is favored and leads to the product
(a)
III. (30 points)
Cl
Cl
N
CH 3
N
Cl
H
1 equivalent
CH 3
Cl
DBN
CH 3
H
Cl
Draw the conformation appropriately:
draw both axial and equatorial positions
for each ring atom that has a substituent. 5
(b)
O
CH 3
S
O
O
N
(i) Using a Newman projection, draw the
conformation that is favored and leads to
the product
OSO2CH 3
N
3
(ii) Selected product
H
DBN
H
H
View the C-C bond as indicated
3
5
B. Complete the following regioselective reactions by drawing the intermediate of highest
energy that forms during the reaction (best resonance contributor if applicable), and draw the
final product(s) as well. If either the intermediate or the regioselected product(s) forms as a
stereoisomeric mixture, draw one and write "+enantiomer" or "+diastereomer" in the box.
(i) highest energy intermediate
predicted to form
(a)
(ii) Final product(s)
Cl
HOCl
Cl
OH
no stereochem
no partial
-1 if "+ enantiomer"
3
(i) highest energy intermediate
predicted to form
(b)
-1 if "+ enantiomer"
4
(ii) Final product(s)
O
H 2O
O
OH
O
H 2SO 4 (cat.)
no partial
-1 if "+ enantiomer"
3
+ diastereomer
4
Name _______________________
Page 4
IV. (28 points)
A. Consider the reaction scheme below, and provide the missing information. Note that
stereochemistry is not considered here.
(a) C8H16O
13C-NMR:
6 signals
CH3OH
HCl
OH
heat
OCH3
H2SO4 (cat.)
dehydration
C9H18O
Major product
3
Electrophilic addition with rearrangement
(b) It has been proposed that the addition product forms as a result of several mechanistic
steps, including two carbocation shifts. Draw this (the most straightforward) curved arrow
mechanism for this transformation. You should choose the appropriate acid/conjugate base
pair for any proton transfers, and be sure to regenerate your acid.
H3C
O H
1
2
H
3
H
4
O
O
O
H3C
CH3
H
H
5
H3C
2 points/intermediate
2 points/mechanism (per step)
Grading stops when a chemically illogical step is shown
OCH3
18
(c) The final product shown will form as (circle the best answer):
a single unique compound
a racemic mixture
a diastereomeric mixture
a mixture of 3 or more
stereoisomers
2
B. The same starting material can be transformed to give a structural isomer of the compound
formed above with no evidence of rearrangement. Draw only the connectivity of the organic
product (C9H18O) that forms, and answer the question about how it forms.
1) BH3
2) H2O2/NaOH
The final product here will form as
(circle the best answer):
C9H18O
OCH3
a single unique compound
a racemic mixture
3) NaH
a diastereomeric mixture
4) CH3I
a mixture of 3 or more stereoisomers
3
2
Name _______________________
Page 5
V. (26 points)
Predict the product(s) in each of the following reactions, using the information given.
(a) If either product forms as a stereoisomeric mixture, draw one and write "+ enantiomer" or "+ diasteromer".
I
OH
HO
I
I2
"+ enantiomer"
OsO4
-1pt
if "+ enantiomer"
3
3
(b)
+ other byproducts
O
Cl
S
H3C
1) NaBr
O
2) NaOCH3
O
OH
N
3
a single optically active
substitution product
O
O
S
OCH3
4
CH3
both products have molecular formula C10H12
13C-NMR:
(c)
13C-NMR:
5 peaks
10 peaks
NaOCH2CH3
I
+
3
3
(d) Provide all the missing information for the following transformation. Each reaction should be balanced.
O
O
O
O
CH3CH2CH2CH2Li
C
O
O
S
O
C
CH3
O
O
C
C
CH
O
C
Li
3
+
CH3CH2CH2CH3
O
S
CH3
O
Li
4