91Ó°ÊÓ

Rank the following groups in order of decreasing priority.

1. ${\mathbf{\text{-F,-NH}}}_{\mathbf{2}}{\mathbf{\text{,-CH}}}_{\mathbf{3}}\mathbf{\text{,-OH}}$
2. ${\mathbf{\text{-CH}}}_{\mathbf{3}\mathbf{,}}{\mathbf{\text{-CH}}}_{\mathbf{2}}{\mathbf{\text{CH}}}_{\mathbf{3}}{\mathbf{\text{,-CH}}}_{\mathbf{2}}{\mathbf{\text{CH}}}_{\mathbf{2}}{\mathbf{\text{CH}}}_{\mathbf{3}}{\mathbf{\text{,-(CH}}}_{\mathbf{2}}{\mathbf{\text{)}}}_{\mathbf{3}}{\mathbf{\text{CH}}}_{\mathbf{3}}$
3. ${\mathbf{\text{-NH}}}_{\mathbf{2}}{\mathbf{\text{,-CH}}}_{\mathbf{2}}{\mathbf{\text{NH}}}_{\mathbf{2}}{\mathbf{\text{,-CH}}}_{\mathbf{3}}{\mathbf{\text{,-CH}}}_{\mathbf{2}}{\mathbf{\text{NHCH}}}_{\mathbf{3}}$
4. ${\mathbf{\text{-COOH,-CH}}}_{\mathbf{2}}\mathbf{\text{OH,-H,-CHO}}$
5. ${\mathbf{\text{-Cl,-CH}}}_{\mathbf{3}}\mathbf{\text{,-SH,-OH}}$
6. ${\mathbf{\text{-°ä≡C±á,-°ä±á(°ä±á}}}_{\mathbf{3}}{\mathbf{\text{)}}}_{\mathbf{2}}{\mathbf{\text{,-CH}}}_{\mathbf{2}}{\mathbf{\text{CH}}}_{\mathbf{3}}{\mathbf{\text{,-CH=CH}}}_{\mathbf{2}}$

Label each stereogenic center as R or S.

a.

b.

c.

d.

e.

f.

g.

h.

Locate the stereogenic centers in each Newman projection and label each center as R or S.

a.

b.

Draw the structures of (S,S)-ethambutol, a drug used to treat tuberculosis that is 10 times more potant than any of its other isomers.

ethambutol

A molecule is achiral if it has a plane of symmetry in any conformation. Each of the following conformations does not have a plane of symmetry, but rotation around a carbon–carbon bond forms a conformation that does have a plane of symmetry. Draw this conformation for each molecule.

a.

b.

Draw the structure of (S)-citalopram, a drug used to treat depression and anxiety that is much more potent than its R enantiomer.

citalopram

Draw the structures for each compound.

1. (R)-3-methylhexane
2. (4R,5S)-4,5-diethyloctane
3. (3R,5S,6R)-5-ethyl-3,6-dimethylnonane
4. (3S,6S)-6-isopropyl-3-methyldecane

Give the IUPAC name for each compound, including the R,S designation for each stereogenic center.

a.

b.

c.

Label the stereogenic centers in paclitaxel, the chapter-opening anticancer drug, as R or S.

What is the maximum number of stereoisomers possible for each compound?

a.

b.

c.