Reaction of potassium hexacyanodinickelate(I) with organic halides

Abstract

Reaction of potassium hexacyanodinickelate (I) (1) with various organic halides in aqueous solutions were examined. Three types of reactions were observed to occur rather selectively depending on the halides used: hydrogenolysis in the case of p-cyanobenzyl bromide and phenacyl bromide; coupling in the case of benzyl, pmethylbenzyl, and p-methoxybenzyl bromide and ¿ra«s-/3-bromostyrene; cyanation in the case of cinnamyl bromide. When the same reaction was carried out in the presence of carbon monoxide, carbonylation reaction occurred easily under mild conditions to give symmetrical ketone or ester. In the presence of acrylonitrile or ethyl acrylate, the reaction of 1 with benzyl bromide gave 4-phenylbutyronitrile and ethyl 4-phenylbutyrate, respectively. Unstable organonickel(II) complexes containing a carbon-nickel bond were postulated as intermediates in these reactions.

Mechanism and Applications of the Photoredox Catalytic Coupling of Benzyl Bromides

“…[1][2][3] The discoveryo ft he biological actions of dihydrostilbenoids, such as those of the combretastatin series, [4] have sparkedr enewed research interest in the synthesis of bibenzyl derivatives. The catalytic mechanism involves the oxidative addition of benzyl halides into low-valent complexes of Mn, [8,14,[25][26][27] Fe, [9,10,28] Ni, [20,22,29] Cu, [16-18, 30, 31] V, [32] Rh, [33] In, [34] Ti, [15,35] and Sm [36,37] that can be generated in the presence of electrons ourcesw ith very negative oxidationp otentials. To expand syntheticr outes to bibenzyls, novel methods that promote the Csp 3 -Csp 3 coupling of halomethyl arenes have been developed.…”

“…[5] However,t his method requires stoichiometric use of excessive reducing reagents, such as Li, [6,7] Mg, [8][9][10][11][12][13][14] Mn, [15,16] Fe, [17,18] Ni, [19] andZ n [20][21][22][23][24] metals, and this limits its syntheticu tility.T he recently developed methods of transition-metal-catalyzed Csp 3 -Csp 3 coupling enable increasedc ontrol over the reaction conditions. The catalytic mechanism involves the oxidative addition of benzyl halides into low-valent complexes of Mn, [8,14,[25][26][27] Fe, [9,10,28] Ni, [20,22,29] Cu, [16-18, 30, 31] V, [32] Rh, [33] In, [34] Ti, [15,35] and Sm [36,37] that can be generated in the presence of electrons ourcesw ith very negative oxidationp otentials. For instance, Zn metal is required to promotet he oxidative additiono fb enzylb romidesi nto aN i complex with at ridentate 2,6-bisoxazolylpyridine ligand.…”

“…The recently developed methods of transition‐metal‐catalyzed Csp 3 –Csp 3 coupling enable increased control over the reaction conditions. The catalytic mechanism involves the oxidative addition of benzyl halides into low‐valent complexes of Mn, Fe, Ni, Cu, V, Rh, In, Ti, and Sm that can be generated in the presence of electron sources with very negative oxidation potentials. For instance, Zn metal is required to promote the oxidative addition of benzyl bromides into a Ni complex with a tridentate 2,6‐bisoxazolylpyridine ligand .…”

Carbon−Carbon Bond Formation with Electrogenerated Nickel and Palladium Complexes

“…These reactions lead to valuable target molecules, such aryl vinyl derivatives, conjugated dienes, and β,γ-or γ,δ-unsaturated compounds. [56] In classical organometallic chemistry, several nickel complexes have been tested stoichiometrically [57] and catalytically [58] for these coupling reactions.…”

Activated Metallic Nickel in the Preparation of Symmetrical 1,3-Diarylpropan-2-Ones From Benzylic Halides and Alkyl Oxalyl Chlorides

“…In the dibenzyl ketone synthesis using benzyl halides and transition metal complexes, [2][3][4][5][6]11,12) readily available benzyl chlorides were not as reactive, and generally gave poor results (up to 51% yield 6)) in spite of effectiveness of benzyl bromides and iodides, and the compatibility with functional groups was not examined. In conclusion these results show that yields are comparable or greater than those using complexes of iron and nickel, and that functional groups such as chloro, bromo, cyano, and carbomethoxy groups are compatible with the reaction conditions employed.…”