Download 1 CH2CH3 C Br H H3C CH2CH3 C Br Cl H3C CH3 C CH3CH2 I Br

Problem Set 6: Stereochemistry-1
Chemistry 260
Organic Chemistry
1-5. Assign absolute stereochemistry (R, S) to the stereogenic centres in each of
the following molecules. Use the following answer choices: (1) R (2) S
1.
2.
H
H 3C
Cl
H3C
Br
C
3.
Br
CH3CH2
C
C
CH2CH3
CH2CH3
4.
CH3
I Br
5.
CH3
C
HOOCCH2
COOH
C
H
NH2
H NH2
6. Which of the following structures correspond to (R)-lactic acid from milk?
(1)
(2)
HOOC
H3C
(3)
CH3
HOOC
OH
C
H
C
CH3
H
(4)
CH3
C
H
H3C
COOH
OH
C
COOH
1
C
H
(5)
H
HO
COOH
OH
OH
7.
The natural amino acid, cysteine, HSCH2C(NH2)H-COOH is in the R
configuration. Which of the following structures correspond to (R)-cysteine?
(1)
(2)
H
H2N
(3)
H2N
H
CH2SH
C
COOH
(4)
C
H
H2N
COOH
C
CH2SH
COOH
(5)
H 2N
H
COOH
COOH
C
H2N
CH2SH
8.
CH2SH
C
H
CH2SH
Given the following five structures, indicate for each pair listed below
whether the structures are identical or isomers.
(a) A and B
(b) A and E
(c) B and E
(d) C and D (you might not get this yet, but give it a try)
9.
By correctly assigning priorites, identify whether the following stereocenters are R
or S.
2
10.
A carboxylic acid with the molecular formula C3H5O2Br is optically active. Draw the
structure of the R-isomer.
11.
Provide a structure for the following compounds.
(a) (R)-3-methylpentanoic acid
(b) (S)-5-ethyl-2-methyloctane
12.
Assign the absolute stereochemistry (R,S) to the stereogenic (asymmetric)
center(s) in each of the following molecules
3
.
13.
Draw all of the constitutional isomers and stereoisomers of compounds named
tribromocyclobutane (all structures must contain a cyclobutane ring). Do not draw any
isomer twice.
4