Reaction with CuCN

The mechanism of action of the cyanation reaction is considered to progress as follows an oxidative addition reaction occurs between the aryl halide and a palladium(O) species to form an arylpalladium halide complex which then undergoes a ligand exchange reaction with CuCN thus transforming to an arylpalladium cyanide. Reductive elimination of the arylpalladium cyanide then gives the aryl cyanide. 

Organozinc halides, RZnI, undergo transmetallation to RCu(CN)ZnI on reaction with CuCN-2LiCl, prepared by reaction of CuCN with anhydrous LiCl in THF. The... 

Recently, functionalized butyl tellurides (e.g., 159) prepared by hydrotelluration of enones 158 (Section 9.13.5.2.4), were reacted with /-butyllithium to give the functionalized alkyllithiums (e.g., 160) which were captured with benzaldehyde or transformed into functionalized alkylcyano cuprates by reaction with CuCN-2 LiCl. In both cases, the obtained organometallics reacted as expected (Scheme 93).251... 

Reduction of the NO2 group followed by diazotization forms the diazonium salt in Step [4], which is converted to a nitrile by reaction with CuCN (Step [5]). 

The regiochemistry of the stoichiometric alkylation (2.2 97.8) is the same as that for the catalyzed reaction with CuCN (2.6 97.4) and is in favor of the 8 2 product. No reaction occurs with n-BuMgBr/CuCl (1 1) because of the formation of the insoluble /i-BuCu. Both regioselectivities observed for the alkylation with n-Bu2CuMgBr (85 15) and CuCl-catalyzed reaction (89 11) are in favor of the 8 2 product. 

Organocopper reagents. Dialkenyl tellurides are readily transformed into copper reagents for conjugate addition, on reaction with CuCN-RLi. When the tellurides contain both alkyl and alkenyl groups they are also transformed into alkenylcuprates. 

In a similar way 4-, 4,5-bis- and 3,4,5-tristrifluoromethyl substimted 1,2-dibromobenzenes 194a-c produces directly Cu complexes of p-tetrafluoromethyl-, P,P -octatrifluoromethyl- and a,p,P -dodecatrifluoromethylphthalocyanines 105a-c [66] in reaction with CuCN in DMF or N-methylpyrrolidone (NMP) (Scheme 26). 

The Sandmeyer reaction involves the replacement of the diazo group by a halogen, usually chlorine or bromine, using copper(I) halides (Figure 13.5). The reaction with CuCN, noted previously, may have the same mechanism (yide infra). 

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