7.4.3 Compounds with 2 or more stereocenters
Let’s look at all of the possible stereoisomers of 2-bromo-3-chlorobutane and how they are related to each other. Two of the stereoisomers, (2S,3R) and (2R,3S) are enantiomers. They are non-identical mirror images of each other. (2R,3R) and (2S,3S) are also enantiomers. They are non-identical mirror images of each other.
But, how are (2R,3S) and (2R,3R) related to each other? They are stereoisomers of each other, but they are not mirror images of each other. There is a name for this relationship. They are diastereomers of each other. Diastereomers are stereoisomers that are not mirror images of each other.
7.4.4 Other examples of diastereomers
Geometric isomers, also called cis-trans isomers, are another example of diastereomers. They are stereoisomers that are not mirror images of each other.
7. Label the following compounds as enantiomers, diastereomers, the same compound, or neither.
7.4.5 Meso Compounds
Compounds that have stereogenic atoms but are achiral are called meso compounds. These compounds typically have stereogenic atoms, but they have a mirror plane of symmetry to prevent them from becoming chiral.
8. Circle each of the following compounds that is a meso compound.
