Diazoalkane 1,3-dipolar cycloaddition

The Diazoalkane 1,3-dipolar cycloaddition is a 1,3-dipolar cycloaddition between a 1,3-dipole diazo compound notably diazomethane and a dipolarophile. When the dipolarphile is an alkene the reaction product is a pyrazoline.

Related Topics:
1,3-dipolar cycloaddition - Diazo compound - Diazomethane - Dipolarophile - Alkene - Pyrazoline

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The reaction product of a cycloaddition between diazomethane and trans-diethyl glutaconate is a 1-pyrazoline. This reaction is 100% regioselective because the diazo terminal nitrogen atom bonds exclusively to the 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 isomerizes to the 2-pyrazoline due to favorable conjugation with the ester group.

Related Topics:
Diazomethane - Trans-diethyl glutaconate - Regioselective - Ester - Syn addition - Isomerizes - Conjugation

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With phenyldiazomethane 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.

Related Topics:
Organic oxidation - Pyrazole

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