Nitrogen-oxygen bonds double bond addition reactions

The carbon-nitrogen triple bond of nitriles is much less reactive toward nucleophilic addition than is the carbon-oxygen double bond of aldehydes and ketones Strongly basic nucleophiles such as Gngnard reagents however do react with nitriles in a reaction that IS of synthetic value... 

Huisgen has reported in 1963 about a systematic treatment of the 1,3-dipolar cycloaddition reaction as a general principle for the construction of five-membered heterocycles. This reaction is the addition of a 1,3-dipolar species 1 to a multiple bond, e. g. a double bond 2 the resulting product is a heterocyclic compound 3. The 1,3-dipolar species can consist of carbon, nitrogen and oxygen atoms (seldom sulfur) in various combinations, and has four non-dienic r-electrons. The 1,3-dipolar cycloaddition is thus An +2n cycloaddition reaction, as is the Diels-Alder reaction. 

Unsaturated fluorinated compounds are fundamentally different from those of hydrocarbon chemistry. Whereas conventional alkenes are electron rich at the double bond, fluoroal-kenes suffer from a deficiency of electrons due to the negative inductive effect. Therefore, fluoroalkenes react smoothly in a very typical way with oxygen, sulfur, nitrogen and carbon nucleophiles.31 Usually, the reaction path of the addition or addition-elimination reaction goes through an intermediate carbanion. The reaction conditions decide whether the product is saturated or unsaturated and if vinylic or allylic substitution is required. Highly branched fluoroalkenes, obtained from the fluoride-initiated ionic oligomerization of tetrafluoroethene or hexafluoropropene, are different and more complex in their reactions and reactivities. 

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