Chemistry 331 - Winter 1996
Elements of Organic Chemistry I

R & S Help

How to view a stereocenter from the proper direction

Note that molecules rarely seem to be written in the most convenient orientation - with the lowest priority group behind the stereocenter.

There are several possible ways to see what the molecule would look like when the lowest priority group is oriented backwards.

Options: (find what works for you)

1) turn the molecule around (without changing the stereochemistry)

2) imagine your eyeball looking from the right viewpoint

3) if you know you're looking from the wrong direction, just reverse the result

4) exchange any two substituents on the stereocenter and you get the opposite enantiomer - do two exchanges and you get the same molecule back again