Question

What is the IUPAC name of this compound?

Answer 1

The IUPAC name is 9-ethyl-2,6-dimethylspiro[4.5]decane.

Your compound is a spiroalkane — a hydrocarbon with two rings and one atom in common. The common atom is a spiro carbon or a spiro centre.

Here are the nomenclature rules.

1. Base the root name on the number of carbon atoms in the rings (10 carbons = decane)

2. Insert the prefix spiro[`x.y`], where `x` and `y` are the numbers of carbon atoms linked to the spiro atom in each ring in ascending order (`"5C + 4C"` gives spiro[4.5]decane).

3. Number the rings starting on the smaller one at the carbon atom closest to a substituent and going through the spiro carbon and around the second ring.

4. List the substituents in alphabetical order in front of the name.

The IUPAC name is 9-ethyl-2,6-dimethylspiro[4.5]decane.