Ring forming reaction

A ring forming reaction or ring-closing reaction in organic chemistry is an umbrella term for a variety of reactions that introduce one or more rings into a molecule. A heterocycle forming reaction is a reaction that introduces a new heterocycle.^[1][2] Important classes of ring forming reactions include annulations^[3] and cycloadditions. Heterocyclic compounds are useful in spectroscopic identification of compounds, purity criteria, and investigating the molecular electronic structures.^[4]

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

• Michael B. Smith & Jerry March, 2007, "March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure," 6th Ed., New York, NY, USA:Wiley & Sons, ISBN 0470084944, see [1], accessed 19 June 2015.
• László Kürti & Barbara Czakó, 2005, "Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms, Amsterdam, NH, NLD:Elsevier Academic Press, 2005ISBN 0124297854, see [2], accessed 19 June 2015.