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Enamine
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==Reactivity== Enamines act as nucleophiles that require less acid/base activation for reactivity than their enolate counterparts. They can offer a greater selectivity with fewer side reactions. Ketone enamines are more reactive than their aldehyde counterparts.<ref>{{cite book|last1=Zvi Rappoport|first1=Zvi|title=Enamines|series=PATAI'S Chemistry of Functional Groups|date=May 1994|isbn= 9780470024768 |doi=10.1002/0470024763}}</ref> Cyclic ketone enamines follow a reactivity trend where the five membered ring is the most reactive due to its maximally planar conformation at the nitrogen, following the trend 5>8>6>7 (the seven membered ring being the least reactive). This trend has been attributed to the amount of p-character on the nitrogen lone pair orbital - the higher p character corresponding to a greater nucleophilicity because the p-orbital would allow for donation into the alkene Ο- orbital. Analogously, if the N lone pair participates in stereoelectronic interactions on the amine moiety, the lone pair will pop out of the plane (will [[Pyramidalization|pyramidalize]]) and compromise donation into the adjacent Ο C-C bond.<ref>{{cite journal|last1=Mayr|first1=H.|title=Structure-Nucleophilicity Relationships for Enamines|journal=Chem. Eur. J.|date=2003|volume=9|issue=10|pages=2209β18|doi=10.1002/chem.200204666|pmid=12772295}}</ref> [[File:Modulating Enamine Nucleophilicity via Stereoelectronicand Inductive Effects.png|center|500px|Modulating enamine nucleophilicity via stereoelectronicand inductive Effects]] There are many ways to modulate enamine reactivity in addition to altering the steric/electronics at the nitrogen center including changing temperature, solvent, amounts of other reagents, and type of electrophile. Tuning these parameters allows for the preferential formation of E/Z enamines and also affects the formation of the more/less substituted enamine from the ketone starting material.<ref name="scripps_Lockner_Nov_07"/>
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