Iron complexes, with alkyl

Subsequent carbonylation of the alkyl-iron complexes with carbon monoxide provides the desired chiral iron-acyl complexes, with essentially complete inversion of configuration at... 

A chiral metal center, as is found in a pseudotetrahedral iron complex with cyclopentudienyl. carbonyl, triphenylphosphine, and ethyl ligands, hus also beer used to address the question of alkyl migration versus carbonyl insertion. Inversion of... 

Reactions of the corresponding ketones have been much less studied, but alkylation reactions appear to be highly antiselective relative to the metal. Some alkylations resulting in the isomerization of the diene geometry have been observed. For example, reaction of (85) with methyl magnesium bromide gives (86) but reaction with methyl lithium affords (87) (Scheme 137). Related reductions of dienone iron complexes with sodium borohydride are also highly antiselective. 

We considered the possibility of the positive effect of small amounts of water on the rate of the transformation of iron complexes with R4NBr and probably on the parameters SPEH and C in the ethylbenzene oxidation, catalyzed (Fe(III)(acac)3 + I NBr. Outer sphere coordination of H20 molecules may promote the stabilization of intermediate zwitterions L2(L ML1 02 ) and as a consequence the increase in the probability of the regioselective addition of 02 to nucleophilic y-C atom of (acac)- ligand can be expected [14], It is well-known that the stability of zwitterions increases in the presence of the polar solvents [14], The H - bond formation between H20 molecule and zwitterion may also promote the proton transfer inside of the zwitterion followed by the zwitterion conversion into the products via Scheme 1 [15], It is known the cases of the increase in the ratio of alkylation s products on y-C atom of the R4N(acac) in the presence of insignificant additives of water ( 10 3 MOJib/n) as compared to the alkylation s reaction in the non proton solvents [16],... 

Equation 1. Alkylation of iron complexes with AIR3 proposed formation of an anionic ligand... 

Equation 2. Alkylation of iron complexes with MAO proposed formation of a cationic complex... 

T. Fujigaya, D.L. Jiang, T. Aida, Switching of spin states triggered by a phase transition spin-crossover properties of self-assembled iron(II) complexes with alkyl-tethered triazole ligands. J. Am. Chem. Soc. 125, 14690-14691 (2003)... 

New tridentate phosphine ligands 46 were synthesized and reacted to form iron carbonyl complexes having the ligands bound in either a tridentate or bidentate fashion (Scheme 56). Reactions of these complexes with alkyl iodides were performed. 

The reaction of electroceduced iron-porphyrin complexes with alkyl halides has yielded a series of iron(III), iron(II), and... 

Cationic (carbene)iron complexes are obtained by alkylation of acyliron complexes with alkylating reagents such as alkyl triflates or Meerwein s salt (Scheme 4-52). " ... 

In (alkene)iron complexes, either neutral or cationic, the electron density at the alkene is reduced. This allows for nucleophilic addition to such complexes. For example, malonates are added to give ethyl malonate derivatives after aqueous workup. Reaction of the intermediate anionic T -alkyl-Fp complexes with alkyl halides leads to migratory insertion of a carbonyl ligand and provides acylated products (Scheme 4-73). ... 

Reaction of ferralactone complexes with amines provides ferralactam complexes. Aromatic amines require the addition of a Lewis acid, whereas alkyl amines react spontaneously. In the course of the reaction, the iron complex moiety moves from one end of the allyl system to the other with concomitant inversion of the configuration at Cl and C4. Reaction of a tricarbonyl(vinylketene)iron complex with electron-deficient alkenes gives (pentenediyl)iron complexes that can be oxidized to tetrasubstituted cyclopropanes. ... 

Even though the electron density of the diene system in tricarbonyl(T -diene)iron complexes is reduced due to 7t-donation to the iron center, reactions with various electrophiles are still possible. Thus, Friedel-Crafts alkylation of (diene)iron complexes with alkoxychloromethanes gives selectively cis- or tra s-(alkoxypenta-2,4-diene)iron complexes depending on the work-up conditions (Scheme 4—110). ... 

Scheme 4-135. Catalytic enantioselective alkylation of (Ti -diene)iron complexes with dialkylzinc reagents.

Using an acetoxy function as leaving group a to the (t -diene)iron complex, this reaction has been employed for the synthesis of the C7-C24 segment of macrolactin 1-Ethoxy-substituted T) -cyclohexadienyliumiron complexes can also be obtained by alkylation of (Ti -cyclohexadienone)iron complexes with triethyloxonium cations (Scheme 4-162). Another general approach to ri -dienyliumiron complexes proceeds via protonation of a noncomplexed double bond in [(l-4-Ti)-l,3,5-triene]iron complexes (Scheme 4-163). - ... 

Easy-to-handle arylboronic compounds can also be reacted in a Suzuki-Miyaura-like fashion with nonactivated alkyl halides using iron catalysis (Scheme 4-239). Two novel iron complexes with sterically hindered diphosphane ligands have been developed for this transformation. Additionally, a magnesium cocatalyst is required. For the mechanism, action of the redox couple Fe(III)/Fe(II) is discussed. This requires the intermediate formation of an alkyl radical species as displayed in Scheme 4-238. " ... 

The porphyrin ligand can support oxidation states of iron other than II and III. [Fe(I)Por] complexes are obtained by electrochemical or chemical reduction of iron(II) or iron(III) porphyrins. The anionic complexes react with alkyl hahdes to afford alkyl—iron (III) porphyrin complexes. Iron(IV) porphyrins are formally present in the carbene, RR C—Fe(IV)Por p.-carbido, PorFe(IV)—Fe(IV)Por nitrene, RN—Fe(IV)Por and p.-nittido, PorFe(IV)... 

ALKYLATION OF DIMEDONE WITH A TRICARBONYL(DIENE)IRON COMPLEX TRlCARBONYL[2-[(2,3,4,5-t))-4-METHOXY 2,4 CYCLOHEXADUEN-l-YLJ-5,5-DIMETHYL-l,3-CYCLOHEXANEDIONE]IRON... 

The iron complex 16 in anhyd benzene was treated with an alkyl halide (excess) and anhyd NaHC03 (1 mol equiv) and the mixture was stirred at 20 "C for 20 h. For acylation, an acyl chloride (1 mol equiv) and anhyd NaHCO, were employed and the mixture was stirred at 20CC for 1-2 h. For decomplexation, the TV-substituted iron complex 17 and a 20-fold molar excess of freshly sublimed Me3NO in acetone were stirred for 20 h at 20 C and the reaction mixture was worked up by chromatography to give 18. 

Iron-acyl enolates such as 1, 2, and 3 react readily with electrophiles such as alkyl halides and carbonyl compounds (see Houben-Weyl, Vol. 13/9a p418). The reactions of these enolatc species with alkyl halides and similar electrophiles are discussed in Section D.1.1.1.3.4.1.3. To date, only the simple enolates prepared by a-deprotonation of acetyl and propanoyl complexes have been reacted with ketones or aldehydes. 

Alkylation of the anion 2 with iodomethane or other haloalkanes provides alkyldicarbonyl(t/5-cyclopentadienyl)iron complexes such as 53,0 (see also Houben-Weyl, Vol. 13/9a, p 209). Migratory insertion of carbon monoxide occurs on treatment with phosphanes or phosphites9 -11 (see also Houben-Weyl, Vol. d3/9a, p257) to provide chiral iron-acyl complexes such as 6. This is the most commonly used preparation of racemic chiral iron-acyl complexes. 

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