Converting Fischer Projections to Zig-zag Structures

Converting Fischer projections to Zig-zag structures can seem daunting at first.  With a little practice it gets much easier.  A good general approach is to draw the side view of the Fischer projection and then convert it to the Zig-zag structure by rotating every other chiral center.

Convert the following Fischer projection into a Zig-zag structure.

  • Recall that all the horizontal bonds are pointing toward you.  Lets use this to our advantage.
  Fischer Projection

Draw the side view.

  • Notice how all the groups on the left side of the Fischer projection are in front of the plane of the paper, while the ones on the left side are behind the plane of the paper.
  • Recall that this conformation is high energy and does not exist for very long in reality.
  Side View

Draw the Zig-zag structure.

  • Rotate every other chiral center 180 degrees so they are more or less pointing down.
  • Notice how the groups are transposed from front to back.
  • You will rotate every other sterecenter starting on the second stereocenter.
  Zig zag Structure

 

Action

Change the number of Stereocenters to 4 and then work through the above example again!

 

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