Ferrocene derivatives. Part II. Arylation

Abstract

It is shown that aryl groups may be introduced into ferrocene by reaction with diazonium salts or with nitrosoacetanilide. FERROCENE can be obtained by the reaction of cyclopentadienylmagnesium bromide (or of the alkali-metal derivatives of cyclopentadiene) with ferric chloride (Kealy and Pauson, Natzlre, 1951, 168, 1039). In Part I * of this series, this method was extended to the preparation of di-, tetra-, and hexa-phenylferrocene from the corresponding phenyl-substituted cyclopentadienes. It was also shown that a small yield of monophenylferrocene can be obtained by using a mixture of cyclopentadiene and phenylcyclopentadiene. The inaccessibility of phenylcyclopentadiene , however, made this route impracticable on a larger scale. We now describe a reaction which makes mono-and di-phenylferrocene readily accessible and can be extended to other arylferrocenes.Although ferrocene undergoes smooth Friedel-Crafts acylation (Woodward, Rosenblum , and Whiting, J . Amer. Chem. Soc., 1952, 74, 3458), other typical aromatic substitution reactions have been limited by the ease of oxidation of ferrocene to metalation with nbutyl-lithium (Benkeser, Goggin, and Schroll, ibid., 1954, 76, 4025). We have found that ferrocene is readily arylated on treatment with diazonium salts.? Adding benzenediazonium sulphate solution to approx. 1 mol. of ferrocene in glacial acetic acid causes steady evolution of gas during several hours at 0". On chromatography of the product some ferrocene is always recovered. Allowing for this, a 65% yield of phenylferrocene (approx. 40% conversion) is obtained together with 9% of diphenylferrocene. A similar reaction occurred in acetone. By the use of other diazonium salts, 9-methoxy-, o-methyl-, and m-chlorophenylferrocene were readily isolated in 3 5 4 % yields. We have also applied the reaction with success to diazotised p-hydroxyaniline, anthranilic acid, and sulphanilic acid.The only limitation of the reaction is again due to the ease of oxidation of ferrocene and was encountered with 2 : 4-dinitroaniline.: a considerable proportion of the ferrocene was converted into femcinium salt, and the diazonium salt reduced to m-dinitrobenzene.

A New Method for the Selective Bridge Functionalization of [2.2]Paracyclophanediene – Indenyl-Annelated [2.2]Paracyclophanedienes and Their Iron Complexes

“…The mean distance hydrofuran complex [FeCl 2 ·(THF) 2 ], led to the mixed-li-between the coordinated carbon atoms and the iron center separated, but characterized as a mixture by NMR spectroscopy. is comparable to that in ferrocene (209 pm) [19] . The repulsion between the centers of high electron density, namely Scheme 5 the aromatic [2.2]paracyclophane system and the metal-ligand coordination sphere causes a bending of the annelated phane moieties by 12°out of the expected sp 2 planarity away from the complexed iron center.…”

1,1′‐Diaryl‐Substituted Ferrocenes: Up to Three Hinges in Oligophenyleneethynylene‐Type Molecular Wires

“…[27] However, in the 1,1Ј-diarylation of ferrocene these procedures suffer either from low yields or reaction times as long as 6 d in the case of the Suzuki-Miyaura coupling reactions. In the search for more practical paths to these compounds we tested the Negishi coupling reaction under microwave irradiation.…”

“…[25] [27] Compound 12 was prepared by following the general procedure using 8 (868 mg, 2.5 mmol) in THF (25 mL), 1.6  butyllithium in hexane (3. [40] [41] Compound 13 was prepared by following the general procedure using 8 (716 mg, 2.1 mmol) in THF (25 mL), 1.6  butyllithium in hexane (2.6 mL, 4.…”

Metallocene Chemistry—a Decade of Progress

“…Conversioils of this sort now constitute the most convenient nleans of preparing these substances, an alternative neth hod being direct synthesis from arylcyclopeiltadienes and iron chlorides (68). Various investigators have studied this reaction using aqueous acetic acid (19,69) or water-ether mixtures (13,70) as the reaction medium. Weinmayr has reported the successful arylation of ferricenium salts in aqueous sulphuric acid (71).…”

“…RIonosubstituted alkyl-, acyl-and aryl-ferrocenes undergo arylation to form primarily heteroannular disubstituted ferrocenes (69,73). Attempts to arylate 1,11-diacylferrocenes, however, result in rupture of the ring-metal bond.…”