CHM 2210-11 Examination 2 A February 23, 2024
INSTRUCTIONS (Read carefully): This examination has three pages of problems, 1 double sided
answer sheet, a periodic table and 1 blank sheet for scratch work. Read each questions carefully.
Write your answers in the spaces provided on the answer sheet. There is a total of 110 points.
REGRADE POLICY: If you have a question about the number of points that you earned on your
graded exam answer sheet, do not make changes or additions to your returned, graded answer
sheet. Bring it to Dr. Krishnan after a lecture or during an office hour, preferably within 2 weeks after
itis returned.
1. (A) [6pts] Draw a Newman projection of the most stable conformation of cis-1-bromo-3-
methylcyclohexane.
(B) [6 pts] Draw the two chair conformers of the compound given below, and circle the more
stable one. If both the conformers are equally stable then circle both.
2. {A) [12 pts] Draw the two chair conformations of
(a) cis-1-(tert-butyl)-4-(2-methylhexyl)cyclohexane
(b) trans-1-Isopropyi-3-hexylcyclohexane.
Put a circle around the most stable conformation in each case.
(B) [12 pts] Give the IUPAC name of the following polycyclic compounds.
(a) (b)
3. Choose the right answer (a/b/c/d) from the following four options provided in each case
{A) [4pts] Among the following isomers of dimethyicyclobutane, which one can exhibit optical
activity?
(a) cis-1,2-dimethylcyclobutane (b) trans-1,2-dimethylcyclobutane
(c) cis-1,3-dimethyicyclobutane (d) trans-1,3-dimethylcyclobutane
{B) [4pts] Which among the following is a conformer of cyclopentane molecule?
(a) Chair (b) Boat (c) Twist (d) Half chair
(C) [4pts] The destabilization of a molecule that results when two of its atoms are too close to each
other is called
(a) Steric strain (b) Torsional strain (c) Angle strain (d) Ring strain
(D) [4pts] Indicate sites of torsional and steric strain in the following
(a) CHy (b) H
i H
() wH G (d) hcnc CHo
3 2
H CH,
H
H H H H H
H CH; H H H H
H,C HiC
, (E) [4 pts] The oxidation state of carbons given in the structure below are respectively (from left to
right in the structure)
/9\/
(a) +2, +1,+3 (b)-2,-1,-3 (c)-1,-2,-3 (d)-2,-1,43
4. Write a structural formula for the following compounds. {(You need to show the wedges and
hashed wedges wherever applicable).
(A) [6 pts] (1R, 3R)-1-bromo-3-ethylcyclohexane
(B) [6 pts] (35, 4S)-3-chloro-4-methylhexane
(C) {6 pts] Pyrrolidine
5. [16 pts] Which of the following terms best describes the pair of compounds shown below:
Enantiomers, diastereomers, constitutional isomers or the same compound?
Br
Hs
u\oH U
HO™
Br CH,
/l\““HCH,CH;
CH,CH,
=N
[20 pts] Salinosporamide A is a potent proteasome inhibitor being studied as a potential
anticancer agent and has the structure shown below with the five chiral centres marked in
asterisk (*). Out of the five chiral centres, four are labelled as ‘@', ‘b’, ‘c’ and ‘d’ in the
structure. In each part of this question, the four bonds to the stereocentre is reproduced in
the same orientation as they are written in this structure. Assign the priorities to each of the
four groups attached to the stereocentre and write the number associated with each group
in the appropriate circle. Then, determine the absolute stereochemical configuration (R/S) at
each chiral centres.
INSTRUCTIONS (Read carefully): This examination has three pages of problems, 1 double sided
answer sheet, a periodic table and 1 blank sheet for scratch work. Read each questions carefully.
Write your answers in the spaces provided on the answer sheet. There is a total of 110 points.
REGRADE POLICY: If you have a question about the number of points that you earned on your
graded exam answer sheet, do not make changes or additions to your returned, graded answer
sheet. Bring it to Dr. Krishnan after a lecture or during an office hour, preferably within 2 weeks after
itis returned.
1. (A) [6pts] Draw a Newman projection of the most stable conformation of cis-1-bromo-3-
methylcyclohexane.
(B) [6 pts] Draw the two chair conformers of the compound given below, and circle the more
stable one. If both the conformers are equally stable then circle both.
2. {A) [12 pts] Draw the two chair conformations of
(a) cis-1-(tert-butyl)-4-(2-methylhexyl)cyclohexane
(b) trans-1-Isopropyi-3-hexylcyclohexane.
Put a circle around the most stable conformation in each case.
(B) [12 pts] Give the IUPAC name of the following polycyclic compounds.
(a) (b)
3. Choose the right answer (a/b/c/d) from the following four options provided in each case
{A) [4pts] Among the following isomers of dimethyicyclobutane, which one can exhibit optical
activity?
(a) cis-1,2-dimethylcyclobutane (b) trans-1,2-dimethylcyclobutane
(c) cis-1,3-dimethyicyclobutane (d) trans-1,3-dimethylcyclobutane
{B) [4pts] Which among the following is a conformer of cyclopentane molecule?
(a) Chair (b) Boat (c) Twist (d) Half chair
(C) [4pts] The destabilization of a molecule that results when two of its atoms are too close to each
other is called
(a) Steric strain (b) Torsional strain (c) Angle strain (d) Ring strain
(D) [4pts] Indicate sites of torsional and steric strain in the following
(a) CHy (b) H
i H
() wH G (d) hcnc CHo
3 2
H CH,
H
H H H H H
H CH; H H H H
H,C HiC
, (E) [4 pts] The oxidation state of carbons given in the structure below are respectively (from left to
right in the structure)
/9\/
(a) +2, +1,+3 (b)-2,-1,-3 (c)-1,-2,-3 (d)-2,-1,43
4. Write a structural formula for the following compounds. {(You need to show the wedges and
hashed wedges wherever applicable).
(A) [6 pts] (1R, 3R)-1-bromo-3-ethylcyclohexane
(B) [6 pts] (35, 4S)-3-chloro-4-methylhexane
(C) {6 pts] Pyrrolidine
5. [16 pts] Which of the following terms best describes the pair of compounds shown below:
Enantiomers, diastereomers, constitutional isomers or the same compound?
Br
Hs
u\oH U
HO™
Br CH,
/l\““HCH,CH;
CH,CH,
=N
[20 pts] Salinosporamide A is a potent proteasome inhibitor being studied as a potential
anticancer agent and has the structure shown below with the five chiral centres marked in
asterisk (*). Out of the five chiral centres, four are labelled as ‘@', ‘b’, ‘c’ and ‘d’ in the
structure. In each part of this question, the four bonds to the stereocentre is reproduced in
the same orientation as they are written in this structure. Assign the priorities to each of the
four groups attached to the stereocentre and write the number associated with each group
in the appropriate circle. Then, determine the absolute stereochemical configuration (R/S) at
each chiral centres.
