Indolyl Phosphine Nickel(II) Fluorido Complexes: Synthesis and Intermediates in Suzuki–Miyaura Cross‐Coupling Reactions

Abstract

The CÀ F bond activation of pentafluoropyridine and 2, 3,5, 2 ] (cod = 1,5cyclooctadiene) in the presence of the phosphine PPh 2 (Ind) (Ind = 3-methyl-2-indolyl) led to the formation of the nickel(II) fluorido bis(phosphine) complexes trans-[Ni(F)(2-C 5 NF 4 ){PPh 2 (Ind)} 2 ] and trans-[Ni(F)(2-C 5 HNF 3 )-{PPh 2 (Ind)} 2 ]. The complexes are characterized by the presence of intramolecular hydrogen bonds between the NH group of the phosphine ligands and the fluorido ligand. Stochiometric model reactions of nickel(II) fluorido complexes with PhB(OH) 2 revealed that the former can be considered as intermediates in Suzuki-Miyaura cross coupling reactions. Catalytic experiments were attempted using 10 mol-% of trans-[Ni(F)(2-C 5 NF 4 ){PPh 2 (Ind)} 2 ] as catalyst and the activities of the PPh 2 (Ind) complex were compared to the ones of an analogous nickel(II) fluorido complex, bearing PPh 3 instead of PPh 2 (Ind) as ligands. The latter exhibited a somewhat lower catalytic activity suggesting a slight influence of the H-bonds in the outer coordination sphere.

C–H and C–F bond activation of fluorinated propenes at Rh: enabling cross-coupling reactions with outer-sphere C–C coupling

“…39 It might additionally be worth noting that examples on the functionalization of fluoroaromatics by cross-coupling reactions involving C–F bond cleavage have been reported, for instance Negishi-type conversions at Ni and Pd by the research groups of Love, Ogoshi and Radius. 13,49–64…”

“…39 It might additionally be worth noting that examples on the functionalization of uoroaromatics by cross-coupling reactions involving C-F bond cleavage have been reported, for instance Negishi-type conversions at Ni and Pd by the research groups of Love, Ogoshi and Radius. 13,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] Other rhodium complexes as catalysts for the derivatization of 5a were then studied using Zn(CH 3 ) 2 as a nucleophile. Accordingly, Zn(CH 3 ) 2 methylates the Rh-F bond of [Rh(F)(PEt 3 ) 3 ] and in the presence of Z-1,3,3,3-tetrauoropropene (5a), the generation of E-1,1,1-triuorobut-2-ene (6a) with 70% conversion was achieved (Table 1, entry 3).…”