5. Chirality

Tamiflu is used for the prevention and treatment of flu. What is the configuration of each of its asymmetric centers?

Limonene exists as two different stereoisomers. The R enantiomer is found in oranges and lemons, and the S enantiomer is found in spruce trees. Which of the following is found in oranges and lemons?

Threonine, an amino acid, has four stereoisomers. The stereoisomer found in nature is (2S,3R)-threonine. Which of the following structures represents the naturally occurring amino acid?

Name the following:

c.

Name the following compounds using R,S designations:

c.

Do the following compounds have the R or the S configuration?

a.

b.

What is the configuration of each of the asymmetric centers in the following compounds?

e.

f.

Citrate synthase, one of the enzymes in the series of enzyme-catalyzed reactions known as the citric acid cycle, catalyzes the synthesis of citric acid from oxaloacetic acid and acetyl-CoA. If the synthesis is carried out with acetyl-CoA that contains radioactive carbon (¹⁴C) in the indicated position, the isomer shown here is obtained.

a. Which stereoisomer of citric acid is synthesized: R or S?

Draw a perspective formula for each of the following:

c. (2S,3R)-3-methyl-2-pentanol

d. (R)-1,2-dibromobutane

Draw a perspective formula for each of the following:

a. (S)-2-chlorobutane

b. (R)-1,2-dibromobutane

Draw structures for the following:

a. (S)-1-bromo-1-chlorobutane

b. (2R,3R)-2,3-dichloropentane

c. an achiral stereoisomer of 1,2-dimethylcyclohexane