5. Chirality

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

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.

a. Draw the equation for this reaction. Show the stereochemistry of the reactant and the product.

b. Has the chiral center retained its configuration during this hydrogenation, or has it been inverted?

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).

(e) chlorocyclohexane

(f) cis-1,2-dichlorocyclobutane

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).

(c)

(d) 1-bromo-2-methylbutane

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).

(a)

(b)

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)?

Naproxen is a commercially available anti-inflammatory sold under the name Aleve.

(a) Assign the absolute configuration as R or S.