text: In organic chemistry, a variety of synthetic procures are particularly useful in closing carbocyclic and other rings; these are termed ring-closing reactions. Examples include:
  * alkyne trimerisation;
  * the Bergman cyclization of an enediyne;
  * the Diels–Alder, between a conjugated diene and a substituted alkene, and other cycloaddition reactions;
  * the Nazarov cyclization reaction, originally being the cyclization of a divinyl ketone;
  * various radical cyclizations;
  * ring-closing metathesis reactions, which also can be used to accomplish a specific type of polymerization;
  * the Ruzicka large ring synthesis, in which two carboxyl groups combine to form a carbonyl group with loss of  and ;
  * the Wenker synthesis converting a beta amino alcohol to an aziridine
  * other reactions, such as an amino group reacting with a hydroxy group, as in the biosynthesis of solanine