Palladium‐catalyzed reductive homocoupling of aryl sulfonates via cleavage of C─O bond at room temperature

Abstract

Palladium‐catalyzed reductive homocoupling of aryl sulfonates has been successfully achieved under mild conditions. This transformation is a new method for the homocoupling reaction of aryl sulfonates at room temperature via the cleavage of C─O bonds, thus providing an alternative synthesis of symmetric biaryls. The reported reductive homocoupling reaction is tolerant of many common functional groups regardless of electron‐donating or electron‐withdrawing nature, making this newly developed transformation important for complementing Ullmann coupling. Experimental Section. Typical procedure for the products.

Chemodivergence between Electrophiles in Cross‐Coupling Reactions

“…[67] However,c ross-coupling of 18 with ap henyls ilane in the presence of aP ,N ligand (39)l eads to preferentialr eactiona tt osylate (Scheme 25 B). [68] Selectivity has also been reported in af ew other lesst raditional couplings of chlorophenyl tosylate 18.F or example, 18 undergoes tosylate-selective reaction in aP d/dppe-catalyzed carbonylative Suzukic oupling, [69] aP d/dppf-catalyzed reductive homocoupling, [70] and aP d/dppf-catalyzed decarboxylative coupling with an a,b-unsaturated carboxylic acid. [71] The different chemoselectivities of the Pd-catalyzedc rosscouplings discussed so far in this section have not been systematically studied or explained.…”

“…Selectivity has also been reported in a few other less traditional couplings of chlorophenyl tosylate 18 . For example, 18 undergoes tosylate‐selective reaction in a Pd/dppe‐catalyzed carbonylative Suzuki coupling, [69] a Pd/dppf‐catalyzed reductive homocoupling, [70] and a Pd/dppf‐catalyzed decarboxylative coupling with an α,β‐unsaturated carboxylic acid [71]…”

C–O-Selective Cross-Coupling of Chlorinated Phenol Derivatives

“…These chloride-selective reactions include Suzuki couplings, 3,14 direct arylations, 15 decarboxylative couplings, 16 and a Hiyama coupling. 17 However, there are also several instances of tosylate-selective reactions including carbonylative Suzuki couplings, 18 Kumada, 19 Hiyama, 20 and Sonogashira couplings, 21 a decarboxylative cross-coupling, 22 a cross-coupling with umpolung aldehydes, 23 a reductive homocoupling 24 and a cross-electrophile coupling, 25 an amination, 26 a Mizoroki-Heck coupling, 27 and an alkoxycarbonylation. 28 Nearly all reported cross-couplings of chloroaryl tosylates involve palladium catalysts.…”