Copper Catalysis in Cycloadditions of Alkynes to Azides

In one approach to catalytic synthesis of 1,2,3-triazoles, copper(l) is introduced to the reaction mixture as Cul. Compounds 1109-1115 are obtained this way. As can be seen in Table 12, a tertiary amine is often added as a base. The reaction conditions are mild and yields of the products are high. In some cases, the reaction can be carried out in water (compound 1115). For the synthesis of triazole 1116, addition of Cu powder is enough to generate catalytic amounts of Cu(l). 

Product Reaction conditions Yield (%) Purpose of synthesis Reference 

R1 = aryl, alkyl, benzyl, PhCH2OCH2, (EtO)2CHCH2, (EtO)2CHCH2CH2 or 2-aminoethyl R2 = aryl, alkyl, cyclohexen-1-yl or (EtO)2CH E+ = l2, C02, CIC02Me, HC02Et, PhCHO, PhNCO, trichloromethyl carbonate, or carbamoyl chloride 

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