Iron compounds reactions with olefins

There is a vast amount of literature on the reactions of iron dodeca-carbonyl with olefins and acetylenes to form a large variety of organo-metallic compounds, and it is neither within the reviewer s aims, nor possible in this limited space, to review comprehensively this branch of cluster chemistry. In reactions such as these the cluster is functioning only as a source of a labile mononuclear species. There are a number of reviews which present an excellent survey of this area 33, 43, 146, 198). 

The diazo reaction with olefins as shown previously is still the fastest method to get hold of mixtures of diastereomers, often, however, with moderate yields due to the lack of reactivity of the olefins. Several nor-chrysanthemic esters [479], alkoxycyclopro-pane carboxylic esters [480,481], which are interesting because of their photostabihty and insecticidal activity [482], and 2,2,3,3-tetramethylcarboxyhc ester [483] were prepared by this route. Asymmetric synthesis using optically active iron carbonyl-olefin complexes afforded 1-R-configurated esters, i.e. precursors for caronaldehyde [484]. The addition of diazopropane across the double bond of olefinic esters via pyrazolines [485, 486] also provides a rapid access to sometimes more complex cyclopropane carboxylic esters with questionable purity, from which the pure compounds can be separated. 

Several diazo compounds, carbene precursors, containing iron, silicon, cadmium, zinc, germanium, lead, tin, mercury, silver, or lithium are knovm. Ferrocenylphenylcarbene and ferrocenylmethylcarbene are found to behave similar to diphenylcarbene in their reactions with olefins (Scheme 54). ... 

Traditionally, iron-based catalysts have been used for FT synthesis when the syngas is coal derived, because of their activity in both FTS and WGS reactions. Complex mixtures of straight-chain paraffins, olefins, and oxygenate (in substantial proportions) compounds are known to be formed during iron-based FTS. Olefin selectivity of iron catalysts is typically greater than 50% of the hydrocarbon products at low carbon numbers, and more than 60% of the produced olefins are a-olefins.13 For iron-based catalysts, the olefin selectivity decreases asymptotically with increasing carbon number. 

When the metallic additive to the intermediate 374 was zinc dihalide (or another Lewis acid, such as aluminum trichloride, iron trichloride or boron trifluoride), a conjugate addition to electrophilic olefins affords 381 . In the case of the lithium-zinc transmetallation, a palladium-catalyzed Negishi cross-coupling reaction with aryl bromides or iodides allowed the preparation of arylated componnds 384 ° in 26-77% yield. In addition, a Sn2 allylation of the mentioned zinc intermediates with reagents of type R CH=CHCH(R )X (X = chlorine, bromine) gave the corresponding compounds 385 in 52-68% yield. ... 

The new Brownsville, Tex., plant for the manufacture of synthetic liquid fuels from natural gas makes use of this reaction to increase the octane number of its product by as much as 20 units. Synthetic naphtha produced over iron catalyst is highly olefinic and contains substantial amounts of straight-chain isomers with terminal double bonds (8). The shifting of these double bonds toward the center of the molecule may be accomplished by vapor-phase treatment employing synthetic cracking catalyst in the fluid state, under mild catalytic cracking conditions. Oxygenated compounds also present are converted under the isomerization conditions to hydrocarbons and water. 

The mechanism of epoxidation has been studied in detail both with P450 enzymes [68] and synthetic metal porphyrins [69], The problem finding a conclusive answer on how the enzymatic reaction proceeds is due to the fact that intermediates have not been detected but inferred by investigating the stereochemistry of product formation. By and large it is safe to say that the reaction depends on the steric hindrance imposed by the olefin s substitutents, the electron donating character of the olefin, and the electron demand of the oxo-iron(IV) porphyrin used. In particular the last aspect makes it difficult to draw conclusions from reactions with model compounds, since these metal porphyrins behave quite differently from native P450 due to the distinct electronic nature of both the metal and the porphyrin. 

Very high endo or cis selectivities have been reported for the reactions of olefins with phenyldiazomethane in the presence of a cationic iron complex11. a-Selenobenzyllithium compounds are carbenoids which transfer the phenylcarbene moiety to olefins with considerable trans preference12. 

In around 1925, the Fisher-Tropsh process, which synthesizes mainly liquid hydrocarbons by the reaction of carbon monoxide with hydrogen at 180-300 C and under 1—300 atm in the presence of nickel, cobalt and iron compounds as catalysts, was developed [81,81a,81b]. This process was used as the process for synthetic petroleum in Germany. However, at present, the production has been continued only in South Africa as state policy. This reaction is revealed to have the action of metal carbonyls as intermediates of the catalysts. In 1938, Roden [82] developed the 0X0 process which produced aldehydes by the reaction of olefins with carbon monoxide and hydrogen in the presence of cobaltcarbonyl type catalysts. 

The following compounds have been obtained from thiete 1,1-dioxide Substituted cycloheptatrienes, benzyl o-toluenethiosulfinate, pyrazoles, - naphthothiete 1,1-dioxides, and 3-subst1tuted thietane 1,1-dioxides.It is a dienophile in Diels-Alder reactions and undergoes cycloadditions with enamines, dienamines, and ynamines. Thiete 1,1-dioxide is a source of the novel intermediate, vinylsulfene (CH2=CHCH=SQ2). which undergoes cyclo-additions to strained olefinic double bonds, reacts with phenol to give allyl sulfonate derivatives or cyclizes unimolecularly to give an unsaturated sultene. - Platinum and iron complexes of thiete 1,1-dioxide have been reported. 

This observation may well explain the considerable difference between metal-olefin and metal-acetylene chemistry observed for the trinuclear metal carbonyl compounds of this group. As with iron, ruthenium and osmium have an extensive and rich chemistry, with acetylenic complexes involving in many instances polymerization reactions, and, as noted above for both ruthenium and osmium trinuclear carbonyl derivatives, olefin addition normally occurs with interaction at one olefin center. The main metal-ligand framework is often the same for both acetylene and olefin adducts, and differs in that, for the olefin complexes, two metal-hydrogen bonds are formed by transfer of hydrogen from the olefin. The steric requirements of these two edgebridging hydrogen atoms appear to be considerable and may reduce the tendency for the addition of the second olefin molecule to the metal cluster unit and hence restrict the equivalent chemistry to that observed for the acetylene derivatives. 

While attempting to prepare an T71-(vinylcarbene)iron complex121 by the alkylation or acylation of an a,/3-unsaturated acylferrate, Mitsudo and Wa-tanabe found122 that the major isolated product was in fact an -vinylketene complex (178), formed presumably by the carbonylation of an intermediate V-vinylcarbene, which may then undergo olefin coordination to the vacant metal site. All attempts to isolate such intermediates, or to observe them by 13C NMR spectroscopy, failed. Only in the reaction between potassium tetracarbonyl -cinnamoy ferrate (179.a) and pivaloyl chloride (180.b) was a side product (181) isolated in appreciable yield. In other reactions, only a trace (<1%) of such a compound was detected by spectroscopy. The bis(triphenylphosphine)iminium(l + ) (PPN) salts of 179.a and 179.b also reacted with 2 equiv of ethyl fluorosulfonate to give 178.g and 178.h in 21 and 37% yield, respectively. All products were somewhat unstable to silica gel, hence the low isolated yields in some cases. 

---