Tosylate, ruthenium-catalyzed direct arylation

Scheme 27 Ruthenium-catalyzed direct arylation with tosylate 71...

Scheme 28 Ruthenium-catalyzed direct arylations with chloride 74 and tosylate 75...

Ruthenium]IV)-carbene complexes can be employed for the direct arylation of alkenes with chloroarenes [130]. Phosphine oxides have also been used as preU-gands in ruthenium-catalyzed direct arylations via C—H bond functionalization using aryl chlorides or aryl tosylates [131-133]. A noteworthy recent finding shows... 

The use of aryl tosylates as electrophiles is attractive, since they can be synthesized from readily available phenols with less expensive reagents than those required for the preparation of the corresponding triflates. More importantly, tosylates are more stable towards hydrolysis than are triflates. However, this greater stability renders tosylates less reactive in transition metal-catalyzed coupling reactions. As a result, protocols for traditional cross-coupling reactions of these electrophiles were only recently developed [1], In contrast, catalytic direct arylations with aryl tosylates were not reported previously. However, a ruthenium complex derived from heteroatom substituted secondary phosphine oxide (HASPO) preligand 72 [81] allowed for direct arylations with both electron-deficient, as well... 

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