View source for Diazoalkane 1,3-dipolar cycloaddition

The '''Diazoalkane 1,3-dipolar cycloaddition''' is a [[1,3-dipolar cycloaddition]] (an organic reaction) between a [[1,3-dipole]] [[diazo]]  compound (notably [[diazomethane]]) and a [[dipolarophile]]. When the dipolarphile is an [[alkene]], the reaction product is a [[pyrazoline]].<ref>{{citation|title=Advanced organic chemistry: reaction mechanisms |first=Reinhard |last=Brückner}}</ref>

The reaction product of a cycloaddition between [[diazomethane]] and [[glutaconic acid|trans-diethyl glutaconate]] is a 1-pyrazoline.<ref>{{Cite journal| doi = 10.1016/j.tetlet.2004.04.097| title = Aza analogs of kainoids by dipolar cycloaddition☆| year = 2004| last1 = Di | first1 = M.| last2 = Rein | first2 = K. S.| journal = Tetrahedron Letters| volume = 45| issue = 24| pages = 4703 }}</ref> This reaction is 100% [[Regioselectivity|regioselective]] because the diazo terminal nitrogen atom bonds exclusively to the alpha-carbon of the [[ester]]. The reaction is also a [[syn addition]], and the configuration in the dipolarophile is preserved. The 1-pyrazoline is unstable and [[isomerization|isomerizes]] to the 2-pyrazoline due to favorable [[conjugated system|conjugation]] with the [[ester]] group.

With [[phenyldiazomethane|diazo(phenyl)methane]] as the reactant the regioselectivity is reversed and the reaction is extended even further by simple air [[organic oxidation]] of the 2-pyrazoline to the [[pyrazole]].  

[[File:Diazoalkane 1,3-dipolar cycloaddition.svg|center|Diazoalkane 1,3-dipolar cycloaddition.]]

Another example of a diazo cycloaddition is a [[diazo-thioketone coupling]].

==References==
{{Reflist}}

{{DEFAULTSORT:Diazoalkane 1,3-Dipolar Cycloaddition}}
[[Category:Cycloadditions]]
[[Category:Heterocycle forming reactions]]