Stereochemistry : Stereochemistry Stereochemistry refers to the
3-dimensional properties and reactions of molecules. It has its own language and terms that need to be learned in order to fully communicate and understand the concepts.
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Definitions : Definitions Stereoisomers – compounds with the same connectivity, different arrangement in space
Enantiomers – stereoisomers that are non- superimposible mirror images; only properties that differ are direction (+ or -) of optical rotation
Diastereomers – stereoisomers that are not mirror images; different compounds with different physical properties
More Definitions : More Definitions Asymmetric center – sp3 carbon with 4 different groups attached
Optical activity – the ability to rotate the plane of plane –polarized light
Chiral compound – a compound that is optically active (achiral compound will not rotate light)
Polarimeter – device that measures the optical rotation of the chiral compound
Plane-Polarized Light : Plane-Polarized Light
Plane-Polarized Light through an Achiral Compound : Plane-Polarized Light through an Achiral Compound
Plane-Polarized Light through a Chiral Compound : Plane-Polarized Light through a Chiral Compound
Polarimeter Measures Optical Rotation : Polarimeter Measures Optical Rotation
Specific Rotation, [α] : Specific Rotation, [α] [α] = α / cl
a = observed rotation
c = concentration in g/mL
l = length of tube in dm
Dextrorotary designated as d or (+), clockwise rotation Levorotary designated as l or (-), counter- clockwise rotation
Specific Rotations of some Common Organic Compounds : Specific Rotations of some Common Organic Compounds Compound [a] # * centers
Penicillin V +233.0 3
Sucrose +66.5 10
Camphor +44.3 2
MSG +25.5 1
Cholesterol -31.3 8
Morphine -132.0 5
Chirality CenterCarbon has four different groups attached : Chirality CenterCarbon has four different groups attached
Enantiomers nonsuperimposible mirror images : Enantiomers nonsuperimposible mirror images
Enantiomeric Excess(Optical Purity) : Enantiomeric Excess(Optical Purity)
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Biological Activity : Biological Activity
SSRI Efficacy depends on Stereochemistry : SSRI Efficacy depends on Stereochemistry
Absolute Configuration : Absolute Configuration
Assign Priority to each Group on Asymmetric Center : Assign Priority to each Group on Asymmetric Center
Lactic Acid : Lactic Acid
C.I.P. Priorities : C.I.P. Priorities
Fischer Projections : Fischer Projections
Assigning Absolute Configuration to Fischer Projections : Assigning Absolute Configuration to Fischer Projections
Rotation of the Projection 90oReverses Absolute Configuration : Rotation of the Projection 90oReverses Absolute Configuration
DiastereomersStereoisomers That Are Not Mirror Images : DiastereomersStereoisomers That Are Not Mirror Images
Fischer Projections with 2 Chiral Centers : Fischer Projections with 2 Chiral Centers
2 Chiral Centers4 Stereoisomers : 2 Chiral Centers4 Stereoisomers
Identical, Enantiomers or Diastereomers? : Identical, Enantiomers or Diastereomers?
Tartaric Acids : Tartaric Acids
Racemic Mixture : Racemic Mixture
Meso CompoundInternal Plane of Symmetry Optically Inactive : Meso CompoundInternal Plane of Symmetry Optically Inactive
2,3,4-trichlorohexaneHow many stereoisomers? : 2,3,4-trichlorohexaneHow many stereoisomers?
n = 3; 2n = 8 : n = 3; 2n = 8
A Carbohydrate : A Carbohydrate
Internal Planes of Symmetry : Internal Planes of Symmetry
Asymmetric Centers on Rings : Asymmetric Centers on Rings
Allenes can be Chiral : Allenes can be Chiral
Mycomycin, an antibiotic : Mycomycin, an antibiotic
Reactions that Generate Chirality Centers Hydrogenation, syn : Reactions that Generate Chirality Centers Hydrogenation, syn
BrominationTrans is formed exclusivelyNo Meso is formed (cis) : BrominationTrans is formed exclusivelyNo Meso is formed (cis)
Bromonium Ion is Opened Equally from Both Sides : Bromonium Ion is Opened Equally from Both Sides
trans alkene + anti addition = MESO : trans alkene + anti addition = MESO
cis Alkene + anti addition = racemic mixture : cis Alkene + anti addition = racemic mixture
Brominations Often Generate Asymmetric Centers : Brominations Often Generate Asymmetric Centers
Asymmetric Center is Generated Racemic Mixture Formed : Asymmetric Center is Generated Racemic Mixture Formed
Asymmetric Induction : Asymmetric Induction
Preparation of (L)-Dopafor Treatment of Parkinson’s : Preparation of (L)-Dopafor Treatment of Parkinson’s
Relevance of Stereochemistry : Relevance of Stereochemistry
One-step synthesis : One-step synthesis
a-(p-isobutylphenyl)propionic acid : a-(p-isobutylphenyl)propionic acid
Model of Thalidomide : Model of Thalidomide
How Sweet it is! : How Sweet it is! Sucralose is 600 times sweeter and does not get metabolized.
Sildenafil (Viagra) and Caffeine : Sildenafil (Viagra) and Caffeine
Radiosensitizer of Choice Until 2004 : Radiosensitizer of Choice Until 2004