XPhos

Abstract: The first general method for the palladium-catalyzed Suzuki−Miyaura and carbonyl enolate coupling of unactivated aryl arenesulfonates was developed utilizing XPhos, 1, and Pd(OAc)2. This is of significant interest because aryl tosylates and aryl benzenesulfonates are more easily handled and considerably less expensive than aryl triflates. This catalyst system effects the coupling of a variety of aryl, heteroaryl, and extremely hindered arylboronic acids with different aryl tosylates, under mild conditions. The same catalyst was employed in the first carbonyl enolate coupling of aryl arensulfonates.

Abstract: The stereochemical course of the stereospecific Suzuki–Miyaura coupling of enantioenriched α-(acetylamino)benzylboronic esters with aryl bromides can be switched by the choice of acidic additives in the presence of a Pd/XPhos catalyst system. Highly enantiospecific, invertive C–C bond formation takes place with the use of phenol as an additive. In contrast, high enantiospecificity for retention of configuration is attained in the presence of Zr(Oi-Pr)4·i-PrOH as an additive.

Abstract: The synthesis of internal benzyl alkynes and 1,2-diarylalkynes has been developed via palladium-catalyzed decarboxylative coupling reactions of alkynyl carboxylic acids with benzyl chlorides or aryl halides. In the presence of Pd(OAc)2 and Xphos (L3), alkynyl carboxylic acids smoothly underwent the reaction with various benzyl halides, providing the corresponding benzyl alkynes in moderate to good yields. It is noteworthy that the optimal conditions are compatible with a wide range of aryl halides including less active aryl chlorides.

Abstract: The Suzuki-Miyaura reaction has become one of the more useful tools for synthetic organic chemists. Until recently, there did not exist a direct way to make the most important component in the coupling reaction, namely the boronic acid. Current methods to make boronic acids often employ harsh or wasteful reagents to prepare boronic acid derivatives and require additional steps to afford the desired boronic acid. The scope of the previously reported palladium-catalyzed, direct boronic acid synthesis is unveiled, which includes a wide array of synthetically useful aryl electrophiles. It makes use of the newly available second generation Buchwald XPhos preformed palladium catalyst and bis-boronic acid. For ease of isolation and to preserve the often sensitive C–B bond, all boronic acids were readily converted to their more stable trifluoroborate counterparts.