Organic Chemistry

PROBLEM-SOLVING STRATEGY

Draw perspective formulas for the following compounds:

a. (R)-2-butanol b. (2S,3R)-3-chloro-2-pentanol

a. First draw the compound—ignoring the configuration at the asymmetric carbon—so

you know what groups are bonded to the asymmetric carbon.

Draw the bonds about the asymmetric carbon.

Put the group with the lowest priority on the hatched wedge. Put the group with the

highest priority on any remaining bond.

Because you have been asked to draw the Renantiomer, draw an arrow clockwise from

the group with the highest priority to the next available bond and put the group with the

next highest priority on that bond.

Put the remaining substituent on the last available bond.

b. First draw the compound, ignoring the configuration at the asymmetric carbon.

Draw the bonds about the asymmetric carbons.

For each asymmetric carbon, put the group with the lowest priority on the hatched wedge.

For each asymmetric carbon, put the group with the highest priority on a bond such that

an arrow points clockwise (if you want the Rconfiguration) or counterclockwise (if you

want the Sconfiguration) to the group with the next highest priority.

H C C

H

C C

CH 3 CHCHCH 2 CH 3

OH

Cl

3-chloro-2-pentanol

(R)-2-butanol

C H

OH

CH 2 CH 3

H 3 C

C H

OH

CH 2 CH 3

C

OH

H

C

CH 3 CHCH 2 CH 3

OH

2-butanol

Section 5.11 The R,SSystem of Nomenclature for Isomers with More than One Asymmetric Carbon 207