Advices For Studying Organic Chemistry

4. Diastereomers must have opposite configurations at some (one or more)
   stereogenic centers, but the same configurations at other stereogenic centers

5.11A MESO COMPOUNDS

C

C

H OH

COOH

COOH

HO H

C

C

HO H

COOH

COOH

HOH

C

C

H OH

COOH

COOH

H OH

C

C

HO H

COOH

COOH

HO H

1

2

3

4

2 R,3R

Mirror 1

2

3

4

1

2

3

2 S,3S

4

2 S,3R

1

2

2 R,3S

3

4

Mirror

C

C

H OH

COOH

COOH

H OH

C

C

HO H

COOH

COOH

HO H

1

2 R,3S

2

3

4

Rotate

1

2

2 S,3R

4

180 o^3

Identical

Figure 5.16 The plane of symmetry of meso-2,3-dibromobutane. This plane
divides the molecule into halves that are mirror images of each other.

5.11B NAMING COMPOUNDS WITH MORE THAN ONE STEREOCENTER

5.12 FISCHER PROJECTION FORMULAS

5.12A FISCHER PROJECTION (Emil Fischer, 1891)