involving fusion of a new ring to a molecule via two new bonds. Some authors use
the term 'annelation
' for the fusion of an additional ring to an already existing one, and 'annulation
' for the formation of a ring from one or several acyclic precursors, but this distinction
is not made generally.
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1083