Name _______________________
Page 1
(a) Molecule 1 was treated with one equivalent of a nucleophile under different conditions of pH, resulting in a
neutral or anionic nucleophile. Structurally isomeric products were obtained under these different conditions,
suggesting that different subtitution mechanisms occurred, with a preference at different electrophilic sites. For
each reaction, predict the product(s) most likely to form. If more than one stereoisomer forms, draw one and write
"+ enantiomer" or "+ diastereomer" in the box.
I. (30 points)
(ii) Substitution product(s)
(i) Substitution product(s)
O
C
O H 3C
O
C
H 3C O
HO
CH 3 Cl
1 equiv.
Cl
O H 3C
O
C
H 3C O
OR
+ diastereomer
CH 3
Na
O
O
C
H 3C
Cl
O
CH 3
1 equiv.
O
O
Cl
1
Cl 3
(iii) Under more aggressive
conditions, with an excess
of a much stronger base,
double elimination is
observed. Draw the
product(s) expected.
Cl
O
C
CH 3
3
C6H 8O
CH 3
H 2C
O
H 3C
O
O
excess, strong base
Cl
1
4
(b) Each of the following reactions produces a pair of distinct products, generally formed in approximately equal
concentrations. Draw these products and state how they are related to each other by circling the best description.
(i)
C11H19 ClO
Cl
HOCl
OH
HO
Cl
4
(ii)
C10H18 Cl2O
OH
OH
Cl2
CH 3
H 3C
Cl
H 3C
Cl
These products are:
(circle one)
enantiomers
diastereomers
structural isomers
2
OH
Cl
Cl
4
These products are:
(circle one)
enantiomers
diastereomers
structural isomers
2
(b) The reaction shown in (ii) above also leads to the formation of the product 2 shown below. Two high-energy
intermediates have been observed to form in this highly stereoselective transformation; draw each. You may
ignore stereochemistry in your drawings.
1st intermediate
OH
OH
2nd intermediate
2 forms as: (check one)
a pair of enantiomers
a pair of diastereomers
Cl
Cl Cl
Cl
Cl
more than 2 stereoisomers
a single product; unique
Cl
2
connectivity
not necessary to show chloride or stereochem at any site
8
3 pts intermediate (all or nothing with charge)
H
O
O
Name _______________________
Page 2
II. (21 points)
Provide all missing information as these syntheses merge. Draw the product(s) that are required for the next step
in the synthesis. Note that only major organic products are given for any one reaction (byproducts, undesired
products are ignored). When providing reagents, be sure to number steps when more than one chemical
transformation is being done. Stereochemistry is not a concern for this first synthesis, so only connectivity is
required for drawings.
13C-NMR: 3 signals
13C-NMR: 2 signals
(a)
Note: Hs may be drawn in
O
LiCH 2CH2CH 3
or Li + -CH2CH2CH 3
2
O
+
O
O H
Note: Hs may be drawn in
2
2
draw all products that are formed in the appropriate boxes
Li
CH 3CH2CH 3
1) O3
2) Zn
Na/NH 3
Br
3
1)
N
O
S Cl
O
major organic product
1) LiH
2)
C 4H 8O
O
S O
O
OH
2) NaBr
O
3) H 2/PdC
3
3
+ other byproducts
(b) Complete the following synthesis using the directions from above.
C20H 20O2
C20H16 O2
H2
O
Pd/CaCO 3
PbO
O
O
O
3
3
1) O3
2) H 2O2/NaOH
O
+
O
OH
2 equivalents
HO
O
O
O
OH
Name _______________________
Page 3
III. (28 points)
(a) Consider each of the following reactions carefully. For each you are asked to provide product(s); if
regioselection is expected, draw major products only. If any product forms as a stereoisomeric mixture, draw
one showing stereochemistry clearly and write "+ enantiomer" or "+ diastereomer" in the box. Answer any other
questions posed about the reaction. You may assume that rearrangement is not part of any of these reactions.
- only one C must be 3D
O
(iii)
(i)
for instance
C
OOH
OsO4
O
O
O
O
O OR
OR
HO
HO
CH2OH
CH2OH
- only one C must be 3D
+ enantiomer 1pt
3
product must be correct
(ii)
If
the
starting
O
material was changed to:
the same
the number of products
would be (circle one): smaller
larger
O
O
+ enantiomer
3
(iv) If
the starting
material was changed to:
O
the same
the number of products smaller
would be (circle one):
larger
2
2
(b) Consider each of the following reactions carefully. For each you are asked to provide product(s); if regioselection
is expected, draw major products only. If any product forms as a stereoisomeric mixture, draw one showing
stereochemistry clearly and write "+ enantiomer" or "+ diastereomer" in the box.
(i)
note, the H may also be drawn
should be on the same side as the OH
H
(iii)
Br 2/CH3OH
1) B 2H 6
OR
OH
+ diastereomer for 1pt
3
Br
+ diastereomer for 1pt
H2
Pd/C
(ii)
OCH3
OR
Br
2) H 2O2/NaOH
OH
OCH3
3
note, the H may also be drawn
OR
+ diastereomer for 1pt
(c)
3
Molecule 3 shown below undergoes bimolecular elimination when treated with a strong base. This reaction
yields only one product. Draw a Newman projection for the conformation of the C1 -C2 bond that undergoes this
elimination reaction (C1 should be in front), and draw the expected product.
Newman projection showing the conformation
of C1 -C2 that undergoes E2
H
CH 3
H
H 3C
C2
C1
Br
Br
3
product of E2 reaction
4
+ 3 for correct molecule (stereochem too)
+ 2 more for correct conformation (anti H, Br) 5
IV. (30 points)
Name _______________________
Page 4
Provide the missing information for each of the transformations of molecule 1 shown below. If more than one
stereoisomer is predicted to form draw one and write "+enantiomer" or "+diastereomer" in the box.
(a) draw all organic product(s)
2pts
- 1pt/missing
H
Cl
O
O
H
N
1)
O
Cl
CH 3
S
H 3C
O
N
H 3C
CH 3
(b)
O
draw reagent(s)
H
O
O
1) NaNH 2
2) NaI
H
O
+
NaI
+
NH 3
2) CH 3I
H
OH H
OCH3
CN H
O
3) NaCN
O
S
4
1
NaI (unnecessary) 4
H 3C
O
- 1pt/missing
(c) Under acidic conditions, and without any indication of rearrangement, alcohol 1 undergoes dehydration to form a
mixture of structurally isomeric products - draw each. If more than one stereoisomer is predicted to form for any
connectivity, draw one and write "+enantiomer" or "+diastereomer" in the box.
C8H12 O2
H
O
O
H 3O
O
H
O
O
H
O
+
H 2O
OH H
H
1
4
(d) Rearrangement (a single shift) provides the only explanation for one of the major products that forms from the
dehydration conditions shown above. Provide the simplest and most efficient curved arrow mechanism for the
formation of the product shown. Use H 3O+ and H 2O appropriately and as needed for proton transfers.
H
O
O
H
O
H
H
H
H
O
O
O
OH H
H
H
O
H
OH2H
H
O
H
H
O
H
H
O
O
1,2 hydride
H
2 points/intermediate + 2 points for resonance
2 points/mechanism (per step)
Grading stops when a chemically illogical step is shown
O
H
O
H
14
C8H12 O2
(e) Other compounds form from the
reaction above. One of which has the
properties indicated. This compound
can also be explained using a single
rearrangement step. Please draw this
other product, based on the data
provided.
13 C-NMR:
5 signals
O
O
4
Name _______________________
Page 5
V. (31 points)
Provide the missing information for each of the following transformations.
(a) When Molecule 1 is treated with a strong, bulky base, only two structurally isomeric products form. Draw each
in the appropriate box, and circle the best description regarding this product mixture.
Products share the molecular formula C12 H 22
(i) 13 C-NMR: 9 signals
Br
O
(ii) 13 C-NMR: 8 signals
K
1
2
2
(iii) circle one:
Only one product is optically active
Both products are optically active
Neither product is optically active
2
(b) However, when Molecule 2 is treated with the same base, one product forms alone.
Br
O
2
K
(S)
(R)
H H
(i) What is the relationship between
molecules 1 and 2?
structural isomers
constitutional
isomers also okay
(iii) Draw the product
(ii) Draw the chair conformation that is
expected to undergo this reaction
Draw
both axial and equatorial
substituents for each ring atom that has a
substituent.
2
(iv) This product is
(circle one):
-5 if wrong molecule
-3 if wrong conformer
2
C12H 22
Br
H
(Z)
optically active
optically inactive
5
2
(c) Follow the fate of Molecule 3 after each of these treatments; both reactions yield a mixture of two products
that share the same molecular formula. Draw each product carefully, showing stereochemistry when
required. And circle the best description for each product set.
(i) C5H10 Cl2O
Cl
(iii) C5H12 O2
Cl Cl
Cl
1) B 2H 6
Cl2
OH
OH
(S)
(R)
(S)
(S)
OH
OH
OH
3
4
(ii) circle one:
Only one product is optically active
Both products are optically active
Neither product is optically active
1
2) NaOH
H 2O2/H2O
OH
OH
4
(iv) circle one:
Only one product is optically active
Both products are optically active
Neither product is optically active
1
v) Provide the complete IUPAC name (including any stereochemistry) for Molecule 3
(S)-3-methylbut-3-en-2-ol
4