Ring forming reaction

A ring forming reaction or ring-closing reaction in organic chemistry is a general term for a variety of reactions that introduce one or more rings into a molecule. A heterocycle forming reaction is such a reaction that introduces a new heterocycle. Important classes of ring forming reactions include annulations and cycloadditions.

Named ring forming reactions
Named ring forming reactions include (not exhaustive):
 * Azide-alkyne Huisgen cycloaddition
 * Bischler–Napieralski reaction
 * Bucherer carbazole synthesis
 * Danheiser annulation
 * Dieckmann condensation
 * Diels–Alder reaction
 * Feist–Benary synthesis
 * Fiesselmann thiophene synthesis
 * Fischer indole synthesis
 * Gewald reaction
 * Hantzsch pyridine synthesis
 * Larock indole synthesis
 * Paal–Knorr synthesis
 * Pictet–Spengler reaction
 * Pomeranz–Fritsch reaction
 * Ring-closing metathesis
 * Robinson annulation
 * Skraup reaction