Organic Chemistry As a Second Language, 3e: First Semester Topics

Published by John Wiley & Sons
ISBN 10: 111801040X
ISBN 13: 978-1-11801-040-2

Chapter 7 - Configurations - 7.7 Drawing Fischer Projections - Problems - Page 163: 7.81


Naming from the top to the bottom, the stereocenters are: 1- "S" 2- "S" 3- "R" 4- "S" The enantiomer of this compound have the same structure, but the left and the right groups are switched with each other.

Work Step by Step

1. Draw wedges in the horizontal lines, and dashes on the vertical lines. Do the steps 2 and 3 for each stereocenter. 2. Now we have to choose one wedge and one dash to switch to "normal" bonds. 3. Determine the configuration of this stereocenter: - Determine the numbers that each group will get. - We will have to use the switch method. - Switch the group number 4 with the group on the dash. - Now, analyzing the new compound: - If the numbers are increasing in counterclockwise direction the new compound is "S", in the opposite case, it is "R" - But, this compound is not the original one, we have switched two groups. - Therefore, the configuration of the original compound is the opposite one. Counting from the top, the stereocenters will be: "S", "S", "R" and "S". 4. To draw the enantiomer, redraw the molecule and just switch the left groups with the right groups.
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