5. Chirality

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

Provide the full name for the following molecule, taking stereochemistry into account.

Prioritize the substituents at each chiral center and then, by comparing them to the models you created in Section 6.3.2, label the absolute configuration as R or S

(f)

Name the following compounds using R,S designations:

c.

What is the configuration of the following compounds? (Use the given structures to answer the question.)

c. ($+$)-lactic acid

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?

3,4-Dimethylpent-1-ene has the formula CH₂=CH—CH(CH₃)—CH(CH₃)₂. When pure (R)-3,4-dimethylpent-1-ene is treated with hydrogen over a platinum catalyst, the product is (S)-2,3-dimethylpentane.

c. The reactant is named (R), but the product is named (S). Does this name change imply a change in the spatial arrangement of the groups around the chiral center? So why does the name switch from (R) to (S)?

Using IUPAC rules, name the following molecules.

(e)

Draw a perspective formula for each of the following:

a. (S)-3-chloro-1-pentanol

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

Name the following alkynes according to the IUPAC rules of nomenclature.

(b)

Provide the full name for the following molecule, taking stereochemistry into account.

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?

Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:

e.

f.

Complete the structure of each of these so that it matches the (R) or (S) configuration associated with the name.

(d)

What is the configuration of the following compounds? (Use the given structures to answer the question.)

a. ($-$)-glyceric acid

b. ($+$)-isoserine