1. Created by Professor William Tam & Dr. Phillis Chang Chapter 5 Stereochemistry Chiral Molecules Copyright © 2014 by John Wiley & Sons, Inc. All rights reserved.

2. About The Authors These Powerpoint Lecture Slides were created and prepared by Professor William Tam and his wife Dr. Phillis Chang. Professor William Tam received his B.Sc. at the University of Hong Kong in 1990 and his Ph.D. at the University of Toronto (Canada) in 1995. He was an NSERC postdoctoral fellow at the Imperial College (UK) and at Harvard University (USA). He joined the Department of Chemistry at the University of Guelph (Ontario, Canada) in 1998 and is currently a Full Professor and Associate Chair in the department. Professor Tam has received several awards in research and teaching, and according to Essential Science Indicators, he is currently ranked as the Top 1% most cited Chemists worldwide. He has published four books and over 80 scientific papers in top international journals such as J. Am. Chem. Soc., Angew. Chem., Org. Lett., and J. Org. Chem. Dr. Phillis Chang received her B.Sc. at New York University (USA) in 1994, her M.Sc. and Ph.D. in 1997 and 2001 at the University of Guelph (Canada). She lives in Guelph with her husband, William, and their son, Matthew. © 2014 by John Wiley & Sons, Inc. All rights reserved.

3. Table of Contents (hyperlinked) 1. Chirality and Stereochemistry Chirality and Stereochemistry 2. Isomerism: Constitutional Isomers and Stereoisomers Isomerism: Constitutional Isomers and Stereoisomers 3. Enantiomers and Chiral Molecules Enantiomers and Chiral Molecules 4. Molecules Having One Chirality Center Are Chiral Molecules Having One Chirality Center Are Chiral 5. More about the Biological Importance of Chirality More about the Biological Importance of Chirality 6. How to Test for Chirality: Planes of Symmetry How to Test for Chirality: Planes of Symmetry 7. Naming Enantiomers: The R,S-System Naming Enantiomers: The R,S-System 8. Properties of Enantiomers: Optical Activity Properties of Enantiomers: Optical Activity 9. The Origin of Optical Activity The Origin of Optical Activity 10. The Synthesis of Chiral Molecules The Synthesis of Chiral Molecules 11. Chiral Drugs Chiral Drugs 12. Molecules with More than One Chirality Center Molecules with More than One Chirality Center 13. Fischer Projection Formulas Fischer Projection Formulas 14. Stereoisomerism of Cyclic Compounds Stereoisomerism of Cyclic Compounds 15. Relating Configurations through Reactions in Which No Bonds to the Chirality Center Are Broken Relating Configurations through Reactions in Which No Bonds to the Chirality Center Are Broken 16. Separation of Enantiomers: Resolution Separation of Enantiomers: Resolution 17. Compounds with Chirality Centers Other than Carbon Compounds with Chirality Centers Other than Carbon 18. Chiral Molecules That Do Not Possess a Chirality Center Chiral Molecules That Do Not Possess a Chirality Center © 2014 by John Wiley & Sons, Inc. All rights reserved.

4. Table of Contents 1. Chirality and Stereochemistry 2. Isomerism: Constitutional Isomers and Stereoisomers 3. Enantiomers and Chiral Molecules 4. Molecules Having One Chirality Center Are Chiral 5. More about the Biological Importance of Chirality 6. How to Test for Chirality: Planes of Symmetry 7. Naming Enantiomers: The R,S-System 8. Properties of Enantiomers: Optical Activity 9. The Origin of Optical Activity 10. The Synthesis of Chiral Molecules 11. Chiral Drugs 12. Molecules with More than One Chirality Center 13. Fischer Projection Formulas 14. Stereoisomerism of Cyclic Compounds 15. Relating Configurations through Reactions in Which No Bonds to the Chirality Center Are Broken 16. Separation of Enantiomers: Resolution 17. Compounds with Chirality Centers Other than Carbon 18. Chiral Molecules That Do Not Possess a Chirality Center © 2014 by John Wiley & Sons, Inc. All rights reserved.

5. In this chapter we will consider:  How to identify, codify, and name the three-dimensional arrangement of atoms and molecules  How such arrangements can lead to unique properties and behaviors © 2014 by John Wiley & Sons, Inc. All rights reserved.

6. 1.Chirality & Stereochemistry  An object is achiral (not chiral) if the object and its mirror image are identical © 2014 by John Wiley & Sons, Inc. All rights reserved.

7.  A chiral object is one that cannot be superposed on its mirror image © 2014 by John Wiley & Sons, Inc. All rights reserved.

8. 1A.The Biological Significance of Chirality  Chiral molecules are molecules that cannot be superimposed onto their mirror images ●One enantiomer causes birth defects, the other cures morning sickness © 2014 by John Wiley & Sons, Inc. All rights reserved.

9. ●One enantiomer is a bronchodilator, the other inhibits platelet aggregation © 2014 by John Wiley & Sons, Inc. All rights reserved.

10.  66% of all drugs in development are chiral, 51% are being studied as a single enantiomer  Of the $475 billion in world-wide sales of formulated pharmaceutical products in 2008, $205 billion was attributable to single enantiomer drugs © 2014 by John Wiley & Sons, Inc. All rights reserved.

11. 2.Isomerisom: Constitutional Isomers & Stereoisomers  Isomers: different compounds that have the same molecular formula ●Constitutional isomers: isomers that have the same molecular formula but different connectivity – their atoms are connected in a different order 2A.Constitutional Isomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

12.  Examples Molecular Formula Constitutional Isomers C 4 H 10 C 3 H 7 Cl © 2014 by John Wiley & Sons, Inc. All rights reserved.

13.  Examples Molecular Formula Constitutional Isomers C2H6OC2H6O C4H8O2C4H8O2 © 2014 by John Wiley & Sons, Inc. All rights reserved.

14. 2B.Stereoisomers  Stereoisomers are NOT constitutional isomers  Stereoisomers have their atoms connected in the same sequence but they differ in the arrangement of their atoms in space. The consideration of such spatial aspects of molecular structure is called stereochemistry © 2014 by John Wiley & Sons, Inc. All rights reserved.

15. 2C.Enantiomers & Diastereomers  Stereoisomers can be subdivided into two general categories: enantiomers & diasteromers ●Enantiomers – stereoisomers whose molecules are nonsuperimposable mirror images of each other ●Diastereomers – stereoisomers whose molecules are not mirror images of each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

16.  Geometrical isomers (cis & trans isomers) are: ●Diastereomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

17. Subdivision of Isomers Isomers (different compounds with same molecular formula) Constitutional Isomers (isomers whose atoms have a different connectivity) Stereoisomers (isomers that have the same connectivity but differ in spatial arrangement of their atoms) Enantiomers (stereoisomers that are nonsuperimposable mirror images of each other) Diastereomers (stereoisomers that are NOT mirror images of each other) © 2014 by John Wiley & Sons, Inc. All rights reserved.

18. 3.Enantiomers and Chiral Molecules  Enantiomers occur only with compounds whose molecules are chiral  A chiral molecule is one that is NOT superimposable on its mirror image  The relationship between a chiral molecule and its mirror image is one that is enantiomeric. A chiral molecule and its mirror image are said to be enantiomers of each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

19. (I) and (II) are nonsuperimposable mirror images of each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

20. 4.Molecules Having One Chirality Center Are Chiral  A chirality center is a tetrahedral carbon atom that is bonded to four different groups  A molecule that contains one chirality center is chiral and can exist as a pair of enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

21.  The presence of a single chirality center in a molecule guarantees that the molecule is chiral and that enantiomeric forms are possible  An important property of enantiomers with a single chirality center is that interchanging any two groups at the chirality center converts one enantiomer into the other © 2014 by John Wiley & Sons, Inc. All rights reserved.

22.  Any atom at which an interchange of groups produces a stereoisomer is called a stereogenic center (if the atom is a carbon atom it is usually called a stereogenic carbon)  If all of the tetrahedral atoms in a molecule have two or more groups attached that are the same, the molecule does not have a chirality center. The molecule is superimposable on its mirror image and is achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

23. (III) and (IV) are nonsuperimposable mirror images of each other same as © 2014 by John Wiley & Sons, Inc. All rights reserved.

24. same as (V) and (VI) are superimposable ⇒ not enantiomers ⇒ achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

25. 4A.Tetrahedral vs. Trigonal Stereogenic Centers  Chirality centers are tetrahedral stereogenic centers Tetrahedral stereogenic center ⇒ chiral (A) & (B) are enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

26. Trigonal stereogenic center ⇒ achiral (C) & (D) are identical  Cis and trans alkene isomers contain trigonal stereogenic centers © 2014 by John Wiley & Sons, Inc. All rights reserved.

27. 5.More about the Biological Importance of Chirality © 2014 by John Wiley & Sons, Inc. All rights reserved.

28.  The activity of drugs containing chirality centers can vary between enantiomers, sometimes with serious or even tragic consequences  For several years before 1963 thalidomide was used to alleviate the symptoms of morning sickness in pregnant women Thalidomide © 2014 by John Wiley & Sons, Inc. All rights reserved.

29.  In 1963 it was discovered that thalidomide (sold as a mixture of both enantiomers) was the cause of horrible birth defects in many children born subsequent to the use of the drug © 2014 by John Wiley & Sons, Inc. All rights reserved.

30. 6.How to Test for Chirality: Planes of Symmetry  A molecule will not be chiral if it possesses a plane of symmetry  A plane of symmetry (mirror plane) is an imaginary plane that bisects a molecule such that the two halves of the molecule are mirror images of each other  All molecules with a plane of symmetry in their most symmetric conformation are achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

31. Plane of symmetry No plane of symmetry achiral chiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

32. 7.Naming Enantiomers: The R,S -System  Using only the IUPAC naming that we have learned so far, these two enantiomers will have the same name: ●2-Butanol  This is undesirable because each compound must have its own distinct name © 2014 by John Wiley & Sons, Inc. All rights reserved.

33.  Rule 1 ●Assign priorities to the four different groups on the stereocenter from highest to lowest (priority bases on atomic number, the higher the atomic number, the higher the priority) 7A.How to Assign (R) and (S) Configurations © 2014 by John Wiley & Sons, Inc. All rights reserved.

34.  Rule 2 ●When a priority cannot be assigned on the basis of the atomic number of the atoms that are directly attached to the chirality center, then the next set of atoms in the unassigned groups is examined. This process is continued until a decision can be made. © 2014 by John Wiley & Sons, Inc. All rights reserved.

35.  Rule 3 ●Visualize the molecule so that the lowest priority group is directed away from you, then trace a path from highest to lowest priority. If the path is a clockwise motion, then the configuration at the asymmetric carbon is (R). If the path is a counter-clockwise motion, then the configuration is (S) © 2014 by John Wiley & Sons, Inc. All rights reserved.

36.  Example ① ③ ④ ② or ③ ①④ ② (H, H, H) (C, H, H) © 2014 by John Wiley & Sons, Inc. All rights reserved.

37. ① ④ ②③ OH Et Me H OH Et Me H Arrows are clockwise (R)-2-Butanol © 2014 by John Wiley & Sons, Inc. All rights reserved.

38.  Other examples ① ④ ② ③ Counter- clockwise (S)(S) ① ④ ② ③ Clockwise (R)(R) © 2014 by John Wiley & Sons, Inc. All rights reserved.

39.  Other examples ① ④ ② ③ Clockwise (R)(R) ●Rotate C–Cl bond such that H is pointed to the back © 2014 by John Wiley & Sons, Inc. All rights reserved.

40.  Other examples ① ④ ② ③ ●Rotate C–CH 3 bond such that H is pointed to the back Counter-clockwise (S)(S) © 2014 by John Wiley & Sons, Inc. All rights reserved.

41.  Rule 4 ●For groups containing double or triple bonds, assign priorities as if both atoms were duplicated or triplicated © 2014 by John Wiley & Sons, Inc. All rights reserved.

42.  Example ① ④ ② ③ (S)(S) © 2014 by John Wiley & Sons, Inc. All rights reserved.

43.  Other examples ① ④ ② ③ (R)(R) ① ④ ② ③ (S)(S) ② ③ © 2014 by John Wiley & Sons, Inc. All rights reserved.

44. 8.Properties of Enantiomers: Optical Activity  Enantiomers ●Mirror images that are not superimposable © 2014 by John Wiley & Sons, Inc. All rights reserved.

45.  Enantiomers have identical physical properties (e.g. melting point, boiling point, refractive index, solubility etc.) Compoundbp ( o C)mp ( o C) (R)-2-Butanol99.5 (S)-2-Butanol99.5 (+)-(R,R)-Tartaric Acid168 – 170 (–)-(S,S)-Tartaric Acid168 – 170 (+/–)-Tartaric Acid210 – 212 © 2014 by John Wiley & Sons, Inc. All rights reserved.

46.  Enantiomers ●Have the same chemical properties (except reaction/interactions with chiral substances) ●Show different behavior only when they interact with other chiral substances ●Rotate plane-polarized light in opposite direction © 2014 by John Wiley & Sons, Inc. All rights reserved.

47.  Optical activity ●The property possessed by chiral substances of rotating the plane of polarization of plane-polarized light © 2014 by John Wiley & Sons, Inc. All rights reserved.

48.  The electric field (like the magnetic field) of light is oscillating in all possible planes  When this light passes through a polarizer (Polaroid lens), we get plane- polarized light (oscillating in only one plane) Polaroid lens 8A.Plane-Polarized Light © 2014 by John Wiley & Sons, Inc. All rights reserved.

49.  A device for measuring the optical activity of a chiral compound 8B.The Polarimeter  =observed optical rotation © 2014 by John Wiley & Sons, Inc. All rights reserved.

50. 8C.Specific Rotation temperature observed rotation wavelength of light (e.g. D-line of Na lamp, =589.6 nm) concentration of sample solution in g/mL length of cell in dm (1 dm = 10 cm) ℓ © 2014 by John Wiley & Sons, Inc. All rights reserved.

51.  The value of  depends on the particular experiment (since there are different concentrations with each run) ●But specific rotation [  ] should be the same regardless of the concentration © 2014 by John Wiley & Sons, Inc. All rights reserved.

52.  Two enantiomers should have the same value of specific rotation, but the signs are opposite © 2014 by John Wiley & Sons, Inc. All rights reserved.

53. 9.The Origin of Optical Activity © 2014 by John Wiley & Sons, Inc. All rights reserved.

54. 9.The Origin of Optical Activity

55. © 2014 by John Wiley & Sons, Inc. All rights reserved. 9.The Origin of Optical Activity

56.  An equimolar mixture of two enantiomers is called a racemic mixture (or racemate or racemic form)  A racemic mixture causes no net rotation of plane-polarized light 9A.Racemic Forms rotation equal & opposite rotation by the enantiomer © 2014 by John Wiley & Sons, Inc. All rights reserved.

57.  A sample of an optically active substance that consists of a single enantiomer is said to be enantiomerically pure or to have an enantiomeric excess of 100% 9B.Racemic Forms and Enantiomeric Excess © 2014 by John Wiley & Sons, Inc. All rights reserved.

58.  An enantiomerically pure sample of (S)-(+)- 2-butanol shows a specific rotation of +13.52  A sample of (S)-(+)-2-butanol that contains less than an equimolar amount of (R)-(–)-2- butanol will show a specific rotation that is less than 13.52 but greater than zero  Such a sample is said to have an enantiomeric excess less than 100% © 2014 by John Wiley & Sons, Inc. All rights reserved.

59.  Enantiomeric excess (ee) ●Also known as the optical purity ●Can be calculated from optical rotations © 2014 by John Wiley & Sons, Inc. All rights reserved.

60.  Example ●A mixture of the 2-butanol enantiomers showed a specific rotation of +6.76. The enantiomeric excess of the (S)-(+)- 2-butanol is 50% © 2014 by John Wiley & Sons, Inc. All rights reserved.

61. 10.The Synthesis of Chiral Molecules 10A.Racemic Forms © 2014 by John Wiley & Sons, Inc. All rights reserved.

63. 10B.Stereoselective Syntheses  Stereoselective reactions are reactions that lead to a preferential formation of one stereoisomer over other stereoisomers that could possibly be formed ●enantioselective – if a reaction produces preferentially one enantiomer over its mirror image ●diastereoselective – if a reaction leads preferentially to one diastereomer over others that are possible © 2014 by John Wiley & Sons, Inc. All rights reserved.

65. 11.Chiral Drugs  Of the $475 billion in world-wide sales of formulated pharmaceutical products in 2008, $205 billion was attributable to single enantiomer drugs © 2014 by John Wiley & Sons, Inc. All rights reserved.

67. 12.Molecules with More than One Chirality Center  In compounds with n tetrahedral stereocenters, the maximum number of stereoisomers is 2 n © 2014 by John Wiley & Sons, Inc. All rights reserved.

68. 12A.How to Draw Stereoisomers for Molecules Having More than One Chirality Center © 2014 by John Wiley & Sons, Inc. All rights reserved.

69.  Start by drawing the portion of the carbon skeleton that contains the chirality centers in such a way that as many of the chirality centers are placed in the plane of the paper as possible, and as symmetrically as possible © 2014 by John Wiley & Sons, Inc. All rights reserved.

70.  Next we add the remaining groups that are bonded at the chirality centers in such a way as to maximize the symmetry between the chirality centers © 2014 by John Wiley & Sons, Inc. All rights reserved.

71.  To draw the enantiomer of the first stereoisomer, we simply draw its mirror image © 2014 by John Wiley & Sons, Inc. All rights reserved.

72.  To draw another stereoisomer, we interchange two groups at any one of the chirality centers All of the possible stereoisomers for a compound can be drawn by successively interchanging two groups at each chirality center © 2014 by John Wiley & Sons, Inc. All rights reserved.

73.  Next we examine the relationship between all of the possible pairings of formulas to determine which are pairs of enantiomers, which are diastereomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

74.  Structures 1 and 2 are enantiomers; structures 3 and 4 are also enantiomers  Structures 1 and 3 are stereoisomers and they are not mirror images of each other. They are diastereomers Diastereomers have different physical properties - different melting points and boiling points, different solubilities, and so forth © 2014 by John Wiley & Sons, Inc. All rights reserved.

75.  Diastereomers ●Stereoisomers that are not enantiomers ●Unlike enantiomers, diastereomers usually have substantially different chemical and physical properties © 2014 by John Wiley & Sons, Inc. All rights reserved.

76.  (I) & (II) are enantiomers of each other  (III) & (IV) are enantiomers of each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

77.  Diastereomers of each other: ●(I) & (III), (I) & (IV), (II) & (III), (II) & (IV) © 2014 by John Wiley & Sons, Inc. All rights reserved.

78. 12B.Meso Compounds  Compounds with two stereocenters do not always have four stereoisomers (2 2 = 4) since some molecules are achiral (not chiral), even though they contain stereocenters  For example, 2,3-dichlorobutane has two stereocenters, but only has 3 stereoisomers (not 4) © 2014 by John Wiley & Sons, Inc. All rights reserved.

79. Note: (III) contains a plane of symmetry, is a meso compound, and is achiral ([  ] = 0 o ). © 2014 by John Wiley & Sons, Inc. All rights reserved.

80.  (I) & (II) are enantiomers of each other and chiral  (III) & (IV) are identical and achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

81.  (I) & (III), (II) & (III) are diastereomers  Only 3 stereoisomers: ●(I) & (II) {enantiomers}, (III) = (IV) {meso} © 2014 by John Wiley & Sons, Inc. All rights reserved.

82. 12C.How to Name Compounds with More than One Chirality Center  2,3-Dibromobutane ●Look through C2–H a bond ① ④ ②③ C2: (R) configuration © 2014 by John Wiley & Sons, Inc. All rights reserved.

83. ●Look through C3–H b bond ① ④ ②③ C3: (R) configuration ●Full name:  (2R, 3R)-2,3-Dibromobutane © 2014 by John Wiley & Sons, Inc. All rights reserved.

84. 13.Fischer Projection Formulas 13A.How To Draw and Use Fischer Projections Fischer Projection © 2014 by John Wiley & Sons, Inc. All rights reserved.

85. Fischer Projection © 2014 by John Wiley & Sons, Inc. All rights reserved.

86. enantiomers  (I) and (II) are both chiral and they are enantiomers of each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

87.  (III) is achiral (a meso compound)  (III) and (I) are diastereomers of each other Plane of symmetry © 2014 by John Wiley & Sons, Inc. All rights reserved.

88. 14.Stereoisomerism of Cyclic Compounds Plane of symmetry a meso compound achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

89. 14A.Cyclohexane Derivatives  1,4-Dimethylcyclohexane Plane of symmetry Both cis- & trans- 1,4-dimethylcyclo- hexanes are achiral and optically inactive The cis & trans forms are diastereomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

90.  1,3-Dimethylcyclohexane Plane of symmetry ●cis-1,3-Dimethylcyclohexane has a plane of symmetry and is a meso compound © 2014 by John Wiley & Sons, Inc. All rights reserved.

91.  1,3-Dimethylcyclohexane NO plane of symmetry ●trans-1,3-Dimethylcyclohexane exists as a pair of enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

92.  1,3-Dimethylcyclohexane ●Has two chirality centers but only three stereoisomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

93.  1,2-Dimethylcyclohexane ●trans-1,2-Dimethylcyclohexane exists as a pair of enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

94.  1,2-Dimethylcyclohexane ●With cis-1,2-dimethylcyclohexane the situation is quite complicated ●(I) and (II) are enantiomers to each other © 2014 by John Wiley & Sons, Inc. All rights reserved.

95. ●However, (II) can rapidly be interconverted to (III) by a ring flip © 2014 by John Wiley & Sons, Inc. All rights reserved.

96. ●Rotation of (III) along the vertical axis gives (I) C1 of (II) and (III) become C2’ of (I) & C2 of (II) and (III) become C1’ of (I) © 2014 by John Wiley & Sons, Inc. All rights reserved.

97. Although (I) and (II) are enantiomers to each other, they can interconvert rapidly  (I) and (II) are achiral © 2014 by John Wiley & Sons, Inc. All rights reserved.

98. 15.Relating Configurations through Reactions in Which No Bonds to the Chirality Center Are Broken  A reaction is said to proceed with retention of configuration at a chirality center if no bonds to the chirality center are broken. This is true even if the R,S designation for the chirality center changes because the relative priorities of groups around it changes as a result of the reaction © 2014 by John Wiley & Sons, Inc. All rights reserved.

99. Same configuration © 2014 by John Wiley & Sons, Inc. All rights reserved.

100. 15A.Relative & Absolute Configurations  Chirality centers in different molecules have the same relative configuration if they share three groups in common and if these groups with the central carbon can be superimposed in a pyramidal arrangement © 2014 by John Wiley & Sons, Inc. All rights reserved.

101.  The absolute configuration of a chirality center is its (R) or (S) designation, which can only be specified by knowledge of the actual arrangement of groups in space at the chirality center (R)-2-Butanol (S)-2-Butanol enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

102. 16.Separation of Enantiomers: Resolution  Resolution – separation of two enantiomers © 2014 by John Wiley & Sons, Inc. All rights reserved.

103.  Kinetic Resolution ●One enantiomer reacts “fast” and another enantiomer reacts “slow” © 2014 by John Wiley & Sons, Inc. All rights reserved.

104.  e.g. © 2014 by John Wiley & Sons, Inc. All rights reserved.

105. 17.Compounds with Chirality Centers Other than Carbon © 2014 by John Wiley & Sons, Inc. All rights reserved.

106. 18.Chiral Molecules That Do Not Possess a Chirality Center © 2014 by John Wiley & Sons, Inc. All rights reserved.

108.  END OF CHAPTER 5  © 2014 by John Wiley & Sons, Inc. All rights reserved.