The Benzylation and Phenylation Reactions of Unsaturated Compounds Using Organo Monohalides and Polynuclear Iron Carbonyl

Abstract

The reaction of iodobenzene and benzyl halides (Cl, Br and I) with Fe3(CO)12 (mole ratio; Fe3(CO)12/R–X=1/3) gave the corresponding symmetrical ketones (18–55.2%). The increasing order of the reactivity of the organo halides to Fe3(CO)12 was as follows: iodobenzene<benzyl chloride<benzyl bromide<benzyl iodide. In the reaction of benzyl chloride with Fe3(CO)12, when two-thirds of the Fe3(CO)12 had been used, or moles equal to benzyl chloride, the yields of the ketones were increased to 87% (total yield). The same reaction in the presence of olefin produced benzylation or phenylation products of the olefin; for example, the reaction of benzyl iodide with Fe3(CO)12 in the presence of acrylonitrile (in tetrahydrofuran) gave 4-phenylbutyronitrile (30.2%) and 4-cyano-6-phenylhexanonitrile (10.0%). When olefin with a higher coordinating ability to iron carbonyl was used, the yields of the benzylated adducts of the olefin decreased, while when the more reactive organo halide was used, the yields increassed. Thus, it was postulated that organo halide reacted with Fe3(CO)12 to form the σ-complex, benzyl(or phenyl)iron carbonyl halide, as an intermediate to the benzylation (or phenylation) products. The benzylation and phenylation reactions proceeded smoothly in a polar solvent (dimethylformamide or ethanol) to give high yields. The benzylation of phenylacetylene did not occur in benzene, but in a polar solvent it proceeded, giving 1,3-diphenylpropane and -propene. The mechanistic aspects of these reactions are discussed below.

Facile reductive coupling of benzylic halides with ferrous oxalate dihydrate

“…Among the iron metal salts and complexes, Fe 3 (CO) 12 -Pyr-N-oxide 9 is reported for the coupling of p-substituted benzyl chlorides to give 1,2-diphenylethanes in ∼ 50% yield. Iron-water, 10 lithium chloroferrate, 11 Na[Fe(CO) 2 -(C 5 H 5 )] 12 and Fe 3 (CO) 12 13 have also been found to be useful low valent coupling agents for benzylic halides.…”

Electrosynthéses de composés carbonylés catalysées par des complexes du nickel: Activation du monoxyde de carbone ou de composés acylés

“…Le classique reactif de Collman Na,Fe(CO), (Collman, 1975, Collman et al, 1977et 1978 1968, Brunet et El Zaizi, 1995 reagissent avec les halogenures organiques pour donner des complexes alkylmetal carbonyle. Leur evolution en complexes acyl-metal carbonyle conduit a l'obtention du produit carbonyle (Colquhoun et al, 1991).…”

“…Le couple zinc-cuivre a ete propose pour la synthese de cetones dissymetriques a partir d'iodures d'alkyle et d'aryle (Tamaru et al, 1983). Pour quelques exemples oh des cetones symetriques sont obtenues avec des rendements moderes, le metal carbonyle lui m6me est l'agent reducteur (Rhee et al, 1968(Rhee et al, , 1978.…”

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

“…Thus, the oxidative addition of benzyl halide to metallic nickel gives benzylnickel(II) halide (4) and the insertion of carbon monoxide, which is formed by decarbonylation of alkyl oxalyl chloride, into the benzyl-nickel bond of complex 4, would afford arylacetyl(II) complex (5). The metathesis of complexes 4 and 5 seems to give (arylacetyl)benzylnickel(II) complex (6), which undergoes reductive elimination to yield 1,3-diarylpropan-2-one (3).…”

“…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.…”