Mizoroki-Heck crosscoupling

In contrast to PPhs, P(c -Tol)3 cannot reduce Pd (OAc)2 to a Pd(0) complex, but a P,C-palladacycle, rran5-di(/r-acetato)-bis[o-(di-o-tolylphosphino)benzyl]dipaIladium (5) is formed via a cyclometallation [27, 55]. The palladacycle 5 is an efficient catalyst for Mizoroki-Heck reactions involving aryl bromides and activated aryl chlorides (i.e. substituted by EWGs) [lj,l,o,s-v, 27, 55]. When 5 is used as catalyst in C—N crosscoupling reactions, Louie and Hart wig [56] have established that the true catalyst is aPd(0) complex, Pd P(o-Tol)3 2 formed by reduction of the palladacycle by the nucleophile (a secondary amine as a hydride donor in the presence of a strong base). 

Dawood KM (2007) Microwave-assisted Suzuki-Miyaura and Heck-Mizoroki crosscoupling reactions of aryl chlorides and bromides in water using stable benzothiazole-based palladium(ll) precatalysts. Tetrahedron 63 9642-9651... 

The literature on the potential applications of Pd-catalyzed crosscoupling reactions for the syntheses of specialty chemicals, pharmaceuticals, and fine chemicals is vast. We begin with two of the earliest examples of industrial applications of Heck-Mizoroki reactions. As shown by (7.4.2.1) and (7.4.2.2), for making the herbicide Prosulfuron and the analgesic R-naproxen, palladium-catalyzed crosscoupling reactions are used in the first steps. 

Structures of three other valuable products 7.61-7.63 are shown later. Total syntheses of all the three include palladium-catalyzed crosscoupling reaction as one of the steps. The synthesis of 7.61, which is used in electronic industries as an adhesive, involves the Heck-Mizoroki reaction, while that of 7.62 and 7.63 includes Negishi and Suzuki-Miyaura reactions, respectively. 

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