Advices For Studying Organic Chemistry

5.11 MOLECULES WITH MORE THAN ONE STEREOCENTER

1. DIASTEREOMERS


2. Molecules have more than one stereogenic (chiral) center: diastereomers


3. Diastereomers are stereoisomers that are not mirror images of each other.
   Relationships between four stereoisomeric threonines
   Stereoisomer Enantiomeric with Diastereomeric with
   2 R,3R 2 S,3S 2 R,3S and 2S,3R
   2 S,3S 2 R,3R 2 R,3S and 2S,3R
   2 R,3S 2 S,3R 2 R,3R and 2S,3S
   2 S,3R 2 R,3S 2 R,3R and 2S,3S


4. Enatiomers must have opposite (mirror-image) configurations at all stereogenic
   centers.

C

C

H NH 2

COOH

CH 3

H OH

C

C

H 2 NH

COOH

CH 3

HO H

C

C

H NH 2

COOH

CH 3

HO H

C

C

H 2 NH

COOH

CH 3

HO

Mi

H

rror Mirror

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

(^4)
(^)
2 R,3R 2 S,3S 2 R,3S 2 S,3R
Enantiomers Enantiomers
The four diastereomers of threonine (2-amino-3-hydroxybutanoic acid)