What is Diels–Alder reaction?
{{Reactionbox | Reference = | Type = Cycloaddition | NamedAfter = [[Otto Diels]]<br />[[Kurt Alder]] | Section3 = {{Reactionbox Identifiers | RSC_ontology_id = 0000006 | RSC_ontology_id_verified= }} | Reaction = {{Reactionbox Reaction | Image = Diels-alder (1,3-butadiene - Ethylene).png | Reactant1 = conjugated (substituted) [[Diene]] | Reactant2 = (substituted) [[Olefin]] | Product1 = (substituted) [[Cyclohexene]] }} }} The '''Diels–Alder reaction''' (DA) is a [[chemical reaction]] between [[organic compound]]s. The reaction causes the [[chemical compound|compounds]] to form a new six-sided compound. This is called a [[cyclohexene]]. A [[conjugated system|conjugated]] [[diene]] joins with an [[alkene]] to make the cyclohexene. This compound looks like a [[ring]].<ref>Diels O. & Alder K. 1928. Synthesen in der hydroaromatischen Reihe. ''Justus Liebig's Annalen der Chemie'' '''460''': 98–122. doi:10.1002/jlac.19284600106. </ref><ref>Diels O. & Alder K. 1929. Synthesis in the hydroaromatic series, IV. Announcement: the rearrangement of malein acid anhydride on arylated diene, triene and fulvene. ''Chemische Berichte'', '''62''', 2081 & 2087.</ref> This reaction was discovered by [[Otto Diels]] and [[Kurt Alder]] in 1928. In 1950, they were given the [[Nobel Prize in Chemistry]] for their work on this reaction. The DA reaction is very useful as it means cyclohexenes can be made with very little [[energy]]. Cyclohexenes are used to make complex organic [[molecule]]s.<ref>Kloetzel M.C. 1948. ''Org. React.'' '''4''', 1–59</ref><ref>Holmes H.L. 1948. ''Org. React.'' '''4''', 60–173.</ref><ref>Kagan H.B. & Riant O. 1992. Catalytic asymmetric Diels Alder reactions. ''Chemical Reviews'' '''92''' (5): 1007. doi:10.1021/cr00013a013</ref><ref>Nicolaou K.C. ''etal'' 2002. The Diels–Alder Reaction in total synthesis. ''Angew. Chem. Int. Ed.'' '''41''', 1668–1698. {{doi|10.1002/1521-3773(20020517)41:10<1668::AID-ANIE1668>3.0.CO;2-Z}}</ref> One of the first uses of the DA reaction was to make [[insectic