Basic IUPAC Organic Nomenclature

Spirocyclic alkanes

• The root name is based on the number of C atoms in the ring structure
• The prefix spiro[x.y] is added. x and y are numbers as defined below.
• The size of the rings is indicated in square brackets by counting the number of atoms in the links that make each ring, x and y, excluding the spirocenter.
• The number of atoms in the links is listed smallest first, i.e. y > x
  
• For substituted spiroalkanes, the rings are numbered starting on the smallest ring adjacent to the spirocenter.
  

Functional group is an alkane, therefore suffix = -ane The ring structure requires the prefix spiro The ring structure is C5 therefore root = pent Excluding the spirocenter, there are two C atoms in each ring = [2.2] spiro[2.2]pentane
Functional group is an alkane, therefore suffix = -ane The ring structure requires the prefix spiro The ring structure is C8 therefore root = oct Excluding the spirocenter, one ring has two C atoms and the other has five C atoms = [2.5] spiro[2.5]octane
Functional group is an alkane, therefore suffix = -ane The ring structure requires the prefix spiro The ring structure is C9 therefore root = non Excluding the spirocenter, one ring has three C atoms and the other has five C atoms = [3.5] There is a C1 substituent = methyl group The lowest locant (first point of difference) = 5 5-methylspiro[3.5]nonane
Functional group is an alkane, therefore suffix = -ane The ring structure requires the prefix spiro The ring structure is C9 therefore root = non Excluding the spirocenter, one ring has three C atoms and the other has five C atoms = [3.5] There is a C1 substituent = methyl group The lowest locant (first point of difference) = 1 1-methylspiro[3.5]nonane

© Dr. Ian Hunt, Department of Chemistry, University of Calgary