Kumada coupling reaction

Low reactive aryl chlorides are converted to the respective organomagnesium species in excellent yields through transition metal catalysis using 2 mol% FeCU (4-6, equation 3). Alternatively, a safe and reproducible method for activation of aryl chlorides or bromides 7 uses microwave irradiation (equation 4). In a synthesis of a novel HIV-1 protease inhibitor, microwave irradiation was essential to generate the starting arylmagnesium halide as well as to promote the subsequent Kumada coupling reaction. ... 

Fig. 30 Vanadium-catalyzed Kumada coupling reactions of alkyl halides...

Fig. 59 Low-valent cobalt-catalyzed radical cyclization/Kumada coupling reactions...

Castle and Widdowson were first to disclose alkyl-alkyl Kumada coupling reactions catalyzed by Pd(dppf)Cl2 [195]. This report was later questioned and corrected by Scott [196]. Matsubara and colleagues established formal Stille-type coupling reactions of perfluoroalkyl halides with allyl, alkynyl, or vinyl stannanes catalyzed by 10 mol% of Pd(PPh3)4, which have to be considered, however, better as radical addition/elimination reactions rather than as coupling reactions (see Sect. 3.1) [184],... 

A third example comes from Clyne et al. [358] and concerns the axial chiral binaphthyl backbone [359,360], itself known from phosphorus chemistry [361]. The synthesis starts from the trifluoromethylsulfonato substituted binaphthyl with a Kumada coupling reaction [291,292] with methytmagnesiumbromide. Oxidation with NBS yields the methyl brominated derivative that can be attached to the imidazole ring. Subsequent methylation results in the bis-imidazolium salt that is deprotonated to the bis-carbene and coordinated to the transition metal halide (Pd, Ni), a rather straightforward reaction sequence (see Figure 3.113). The overall yield for the four-step reaction to the bis-imidazolium salt is surprisingly good (65%). 

Catalyst development for Pd-catalyzed Kumada coupling reactions. 

Scheme 31. Kumada coupling reactions of (hetero)aryl halides with aryl Grignard reagents [84b, 118] and oxidative photocyclization towards benzo[s]picene (67, [84b])...

Having observed how Grignard reagents converted their aliphatic pincer Ni-Br complex 17 to the corresponding Ni-R complex, the group of Zargarian [23] applied 17 as a catalyst for the Kumada coupling reaction (Scheme 8.17). As opposed to its... 

Cazin and coworkers investigated the activity of dimers analog to 10 as catalysts for Kumada coupling reactions [32]. Of the four complexes tested (NHC = IPr, SlPr, IMes, and SlMes) the SlPr-bearing complex proved to be the most effective for the synthesis of tri- and tetra-ori//o-substituted biaryls, under relatively mild reaction conditions and in good yields. 

Fig. 6 Synthesis of alkylated thiophenes via Kumada coupling reaction 3.3.1 Kumada Coupling Reaction...

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