Chapter 7 Stereochemistry Enantiomers of bromochlorofluoromethane Nonsuperimposable mirror

Chapter 7 - Stereochemistry Enantiomers of bromochlorofluoromethane Non-superimposable mirror images – Enantiomers

YSU Figure 7. 1

7. 12 Optically active molecules of biological importance YSU

YSU $100 billion sales worldwide in 2000 Account for 32% of the $360 billion total drug sales

7. 2 The Chirality Center Carbon atom is asymmetric C is a stereogenic center Enantiomers are stereoisomers since the atoms at the stereogenic carbon are arranged differently in space. YSU

7. 3 Symmetry in achiral structures Mirror images of chlorodifluoromethane are superimposable Figure 7. 2 Achiral i. e. not chiral YSU

7. 4 Optical activity Figure 7. 4 Typical polarimeter setup : [a]D = 100 x (rotation)/(cell length) x (concentration) YSU

7. 8 Enantiomers same physical properties except rotation of plane polarized light one enantiomer positive rotation (+) other negative rotation (-) YSU

Which molecules contain chiral (stereogenic) centers? The stereogenic C must have 4 different groups attached YSU

7. 5 Absolute and Relative Configuration Absolute Configuration – Actual arrangement of substituents in space (+)-2 -butanol and (-)-2 -butanol, but which is which? Relative Configuration - Configuration relative to another compound. Pre-1951, compounds could be related to each other but the absolute configuration was not able to be determined. YSU

7. 6 Nomenclature - Use of the Cahn-Ingold-Prelog System (R) and (S) R enantiomer S enantiomer R - Rectus - the clockwise arrangement of groups S - Sinestre - the counterclockwise arrangement of groups YSU

7. 6 Nomenclature - Use of the Cahn-Ingold-Prelog System YSU

7. 7 Fischer projection formulas Figure 7. 5 YSU

7. 9 Reactions that create a Chirality Center Figure 7. 6 YSU

7. 10 Chiral molecules with two Chirality Centers Figure 7. 7 YSU

7. 10 Representations of (2 R, 3 R)-dihydroxybutanoic acid Figure 7. 8 YSU Conversion of “zig-zag” picture to Fischer projection All the same molecule: (a) and (b) differ only by bond rotation ; (b) leads to correct Fischer projection

7. 10 Chiral molecules with two Chirality Centers YSU

7. 11 Achiral molecules with two Chirality Centers Figure 7. 9 YSU

Meso-2, 3 -butanediol Figure 7. 10 YSU

7. 12 Stereogenic centers in cholic acid Figure 7. 11 YSU

7. 12 Optically active molecules of biological importance YSU

7. 13 Reactions that produce diastereomers Figure 7. 12 YSU

7. 13 Reactions that produce diastereomers Figure 7. 12 YSU

7. 14 Resolution of a chiral substance into its enantiomers Figure 7. 13 YSU

Not covering 7. 15 and 7. 16 YSU