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Homework Help: How do I add S/R configuration to this?

  1. Feb 11, 2017 #1
    Edit by Mentor: thread moved from the other forum, hence no template used.


    The problem tells me to determine the S/R configurations of each chiral center in the compound, which I have drawn in the picture above. As you can see the numbers assigned by atomic # are not in order. How would I go about determining configuration in this case?
  2. jcsd
  3. Feb 12, 2017 #2


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    Follow the procedure described here: http://web.chem.ucla.edu/~harding/tutorials/stereochem/r_s.html (you've already completed step #1, not just move onto steps #2 and 3).

    Basically, you rotate the molecule so that the group with the lowest priority (#4) is pointing away from you. Then you look at the arrangement of the groups with priority #1-3. If these are arranged in a clockwise manner (i.e. you move clockwise going form #1 to #2 to #3) then the stereocenter is R. If they arranged in a counterclockwise manner, then the stereocenter is S.

    If you have trouble visualizing and rotating the stereocenter in your head, try building a physical model that you can rotate for yourself.
  4. Feb 16, 2017 #3
    following on from what was said previously, you've basically already done it with your drawing, as the H (lowest priority group) is pointing away from you.
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