Selective carbon-carbon bond formation by cross-coupling of Grignard reagents with organic halides. Catalysis by nickel-phosphine complexes

Metal-catalyzed activation of ethers via C–O bond cleavage: a new strategy for molecular diversity

“…Strikingly, the authors found a different reaction outcome in the absence of COD. Thus, the stoichiometric reaction of 2-methoxy naphthalene with Ni(0) complexes containing PCy 3 such as 2 CO and naphthalene (Scheme 29, top), suggesting that the hydride transfer might not require the use of silanes. In analogy with recent studies using pincer-type complexes, 57 the authors explained such result by a sequence consisting of oxidative addition into the C(sp 2 )-OMe bond followed by β-hydride elimination, C-H functionalization and H 2 extrusion (Scheme 29, bottom).…”

“…Specifically, the authors favoured an innovative mechanistic scenario based upon the intermediacy of Ni(I)-SiR 3 species (Scheme 31). 67 The proposed redox-neutral mechanism consisted of an initial migratory insertion followed by a [1,2]-shift with concomitant release of R 3 SiOMe and a final σ-bond-metathesis that recovers back the active Ni(I)-SiR 3 species.…”

“…Although such mechanistic study was focused on a rather specific reaction of aryl ethers, it is worth noting that the authors demonstrated that "classical" oxidative addition cannot occur if Ni(COD) 2 and tricyclohexylphosphine are utilized. These results reasonably leave some doubt about the proposed mechanisms for C-O cleavage in aryl ethers under a Kumada-Corriu, Negishi or Suzuki-Miyaura regime.…”

Cobalt-catalyzed mono-coupling of R 3 SiCH 2 MgCl with 1,2-dihalogenoethylene: a general route to γ-substituted ( E )-allylsilanes

“…As can be seen from Table 2 summarizing the several representative results, 1 with methyl as well as normal and secondary alkyl and aryl groups could be readily prepared by the Ni-catalyzed coupling with the corresponding Grignard reagent (Kumada-Tamao reaction). 5 It is noteworthy that the Suzuki-Miyaura coupling 9 of bromide 2b with boranes was effective for synthesis of 1 having a functional group as shown in entry 5.…”

“…First, we investigated a transition metal-catalyzed coupling reaction of (E)-1,2-dichloroethylene (>99% E), which is commercially available at low price, with TMSCH 2 MgCl to find conditions for selective production Table 1 summarizing the results, nickel-catalyzed reactions 5 afforded a mixture of (E)-3-trimethylsilyl-1-chloro-1-propene (2a) and 1,4-bis(trimethylsilyl)-2-butene (3) (entries 1-4). 6 It was noteworthy that the reaction with Ni-PPh 3 complexes gave 2a predominantly (entries 1 and 2) but Ni-complexes with a bidentate phosphine ligand such as Cl 2 Ni(dppp) and Cl 2 Ni(dppb) catalyzed production of 3 mainly (entries 3 and 4).…”