ARYL MESYLATES IN METAL-CATALYZED HOMO-COUPLING AND CROSS-COUPLING REACTIONS .4. SCOPE AND LIMITATIONS OF ARYL MESYLATES IN NICKEL-CATALYZED CROSS-COUPLING REACTIONS

This paper describes the synthetic utility of aryl mesylates derived f rom phenols in various transition metal-catalyzed cross-coupling react ions. The Ni(0)-catalyzed cross-couplings of aryl mesylates with organ ometallic carbanion synthons (organotin, -magnesium, and -zinc compoun ds) are described. It is demonstrated that Stille-type coupling reacti on based on organotin compounds results in low yields due to the slugg ish transmetalation step of the reaction cycle. Good to high yields of cross-coupled products are obtained by using more reactive organomagn esium and -zinc compounds as coupling partners. The Ni(0)-catalyzed cy anation of aryl mesylates is also described. Various aryl mesylates ar e converted to aryl nitriles in high yields by reaction with KCN in th e presence of Ni(0) catalyst in DMF. In addition, the Ni(0)-catalyzed aromatic nucleophilic substitution reaction of aryl mesylates with the heteroatom-nucleophile, benzenethiolate anion, is also presented.