Editing Cope reaction (section)

==Mechanism and related eliminations==
The reaction proceeds through the [[Ei mechanism|E<sub>i</sub> pathway]], with an intramolecular, cyclic 5-membered [[transition state]].{{ref|1}}  Consequently, the elimination product is always [[syn elimination|''syn'']] and rarely occurs with [[piperidine|6-membered rings]].  ([[Pyrrolidine|Rings with 5]] or 7 or more members undergo the reaction just fine.)<ref>{{cite book |last1=March |first1=Jerry |url=https://archive.org/details/marchsadvancedor00smit_198 |title=March's advanced organic chemistry: reactions, mechanisms, and structure. |last2=Smith |first2=Michael B. |publisher=Wiley-Interscience |year=2007 |isbn=978-0-471-72091-1 |edition=6th. |page=[https://archive.org/details/marchsadvancedor00smit_198/page/n1541 1525] |url-access=limited}}</ref><ref>''Amine Oxides. VIII. Medium-sized Cyclic Olefins from Amine Oxides and Quaternary Ammonium Hydroxides'' Arthur C. Cope, Engelbert Ciganek, Charles F. Howell, Edward E. Schweizer [[J. Am. Chem. Soc.]], '''1960''', 82 (17), pp 4663–4669 {{doi|10.1021/ja01502a053}}</ref><ref>''Amine Oxides. VII. The Thermal Decomposition of the N-Oxides of N-Methylazacycloalkanes'' Arthur C. Cope, Norman A. LeBel; [[J. Am. Chem. Soc.]]; '''1960'''; 82(17); 4656-4662. {{doi|10.1021/ja01502a052}}</ref>  
[[File:CopeReactionJACS82-4656.svg|alt=intramolecular Cope reaction|center|261x261px]]
This [[organic reaction]] is closely related to the [[Hofmann elimination]],{{ref|1}} but the [[base (chemistry)|base]] is a part of the [[leaving group]].  [[Sulfoxide]]s can undergo an essentially identical reaction to produce [[sulfenic acid]]s, which is important in the antioxidant chemistry of garlic and other [[Allium|''allium''s]]. [[Selenoxide]]s likewise undergo [[selenoxide elimination]]s.