Huisgen cydoaddition

Azide end-functionalized polymers have become a major building block in polymer chemistry due to their use in the Huisgen cycloaddition reaction. This reaction involves the reaction of an alkyne with an azide in the presence of a Cu catalyst to form the corresponding 1,3-cydoaddition product. The reaction is considered a dick reaction due to its high efSdency and rdativdy short reaction time. The Huisgen cydoaddition reaction has been used to prepare a variety of end-functionalized polymers starting from the azide end-functionalized polymer. Lutz et was the first to... 

No single examples have been reported so far for the catalyzed asymmetric diazoalkane cydoadditions. Based on the kinetic data on the relative reaction rates observed by Huisgen in the competitive diazomethane cydoadditions between 1-alkene and acrylic ester (Scheme 7.32), it is found that diazomethane is most nu-deophilic of all the 1,3-dipoles examined (kaciyiate/fci-aikene = 250000) [78]. Accordingly, the cydoadditions of diazoalkanes to electron-defident alkenes must be most efficient when catalyzed by a Lewis acid catalyst. The author s group has become aware of this possibility and started to study the catalyzed enantioselective diazoalkane cydoadditions of 3-(2-alkenoyl)-2-oxazolidinones. 

Triazoks were synthesized from simple starting materials without the need for additional catalyst. Organic azides, generated in situ from alkyl halides and sodium azide, were reacted with acetylenes using the copper-catalyzed Huisgen 1,3-dipolar cydoaddition. 

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