Acyliron complexes

Acyliron complexes have found many applications in organic synthesis [40]. Usually they are prepared by acylation of [CpFe(CO)2] with acyl chlorides or mixed anhydrides (Scheme 1.13). This procedure affords alkyl, aryl and a,P-unsaturated acyliron complexes. Alternatively, acyliron complexes can be obtained by treatment of [Fe(C5Me5)(CO)4]+ with organolithium reagents, a,P-Unsaturated acyliron complexes can be obtained by reaction of the same reagent with 2-alkyn-l-ols. Deprotonation of acyliron complexes with butyllithium generates the corresponding enolates, which can be functionalized by reaction with various electrophiles [40]. 

Acyliron complexes with central chirality at the metal are obtained by substitution of a carbon monoxide with a phosphine ligand. Kinetic resolution of the racemic acyliron complex can be achieved by aldol reaction with (1 R)-( I (-camphor (Scheme 1.14) [41], Along with the enantiopure (R, c)-acyliron complex, the (Spe)-acyliron-camphor adduct is formed, which on treatment with base (NaH or NaOMe) is converted to the initial (SFe)-acyliron complex. Enantiopure acyliron complexes represent excellent chiral auxiliaries, which by reaction of the acyliron enolates with electrophiles provide high asymmetric inductions due to the proximity of the chiral metal center. Finally, demetallation releases the enantiopure organic products. 

Aromatic ketones (c/., 4, 461, 463).1 The acyliron complexes (2), prepared from Na2Fe(CO)4 as shown, have rather low reactivity with alkyl halides. However,... 

Decarbonylation of a-acyliron complexes by photolysis (Section 3.5) is the primary method for the preparation of a-aryliron complexes. Alternatively, cr-aryliron complexes can be prepared by the method of Beletskaya from FpNa (5). For example, the /7-tolyl analog has been recently prepared in order to study the C H activation of benzene (equation 3). ... 

The acyliron(0) complex (102) has been isolated and subjected to the same nucleophilic displacement (or equivalently oxidative addition) with excellent correlation (Scheme 39). The same species is also readily available from acid chlorides (i.e. formation of 103), but the overall process has not been widely used in the synthesis of ketones (Scheme 40). The final step of the process, a reductive elimination of acyliron(II) complex (104) or (105), is quite rapid and it has not been possible to isolate and identify the presumed intermediates in this case (Scheme 41). Since the oxidative addition of the acyliron complex with the alkyl halide is extremely mild, the corresponding ketone formed in the reaction is not subject to attack by organometallic reagents and no tertiary tdcohol is formed. 

Based on the observation made by Ryang and Tsutsumi [67] and also by Wata-nabe at Kyoto [68], Collman and others have developed a series of synthetic reactions via anionic acyliron complexes (Eqs. (5.58) and (5.59)) [69-71],... 

Figure 7 Proposed transition states involved in the addition of the enolate of acyliron complex (175) to imines ...

Cleavage of carbon-metal bonds. When acyliron complexes such as those derived from carbonylation of (i7 -allyl)Fe(CO)2NO are treated with an alcoholic iodine solution, esters are obtained. Zirconacyclopentenes, which are formed by... 

Potassium tetracarbonylferratej 18 cr own-6 poly ether 1,4-Addition with acyliron complexes... 

Herndon JW, Wu C (1989) Stereoselectivity in the reaction of acyliron complexes with allylstannanes. Tetrahedron Lett 30(42) 5745-5746. doi 10.1016/S0040-4039(00)76186-7... 

Herndon JW, Wu C, Harp JJ, Kreutzer KA (1991) Exploration of the [3-h2] cycloaddition reaction between allylstannanes and a, p-unsaturated acyliron complexes. Synlett 1 1-10. doi 10.1055/ s-1991-20610... 

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