IUPAC Systematic Naming for Compounds with Stereochemistry

Summary Sheet: Naming Molecules with Stereochemistry

As a reminder, remember the Wize General Naming Rules:

1. Identify and name the longest carbon chain
2. If present, assign stereochemistry (R/S or E/Z)
3. Identify and name any substituents on the carbon chain
4. Give these substituents the appropriate 'address'
5. Add substituent names as a prefix to the carbon chain
6. Change suffix of the carbon chain if necessary (for functional groups)

For this lecture, we are going to focus on naming compounds with stereochemistry (R/S stereogenic centres or cis/trans double bonds). Take for example the following two compounds:

I included the carbon atom numbering because you know how to do that now! The alkene (with blue numbering) is an E-alkene (AKA trans). The IUPAC name is (E)-3-methylpent-2-en-2-ol. The E notation comes first and is in brackets. Since there is only one double bond, you don't have to designate which alkene has an E double bond is.

But what about when there's two stereocentres? Let's take the second compound, with numbering shown in red. The IUPAC name is (2R,4R)-2-bromo-4-chloroheptane. Again, I'm taking for granted your ability to label stereocentres as R and S... That's covered in another section. Now, due to the presence of two stereogenic centres, we need to designate the location of each stereocentre with numbers.

Example: Naming Molecules with Stereochemistry

Name the following molecule:

Example: Naming Molecules with Stereochemistry

Name the following molecule: