How do you draw a diastereomer?

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Answer 1 · 2016-09-01T01:15:28

You change the configuration of one of the chiral centres.

Diastereomers are stereoisomers that are not superimposable and are not mirror images of each other.

A compound must have at least two chiral centres to have diastereomers.

Let's look at a Compound #"A"# with two chiral centres.

#"C2"# and #"C3"# are chiral centres.

If we change the configuration at #"C2"#, we get Compound #"B"#.

This is not a mirror image of #"A"#, nor is it superimposable with #"A"#. It is a diastereomer of #"A"#.

Now, let's change the configuration of just #"C3"# to get Compound #"C"#.

This is also a diastereomer of #"A"#.

BUT, if we change the configuration of both carbon atoms, we get Compound #"D"#.

This is nonsuperimposable on #"A"#.

However, it is a mirror image of #"A"#, because both #"OH"# groups are on dashes instead of on wedges.

#"A"# and #"D"# are enantiomers.