Allylic iron-catalyzed

Durandetti et al. have described iron-catalyzed electrochemical allylation of carbonyl compounds with allylic acetates (Equation (27)).333 In the case of aldehydes, slow addition of the corresponding aldehyde is required in order to avoid pinacol formation. With crotyl acetate (R3 = Me), the reaction proved to be highly regioselective, providing almost exclusively branched homoallylic alcohols 150. 

Iron-catalyzed Allylic Oxidations 3.2.2.1 Simple Iron Salts... 

From the discussion above, the following conclusions can be drawn. Apart from some selected examples, the issue ofchemoselectivity and catalytic activity in iron-catalyzed allylic hydroxylation has not so far been solved. In particular, synthetically useful methods with a broad scope concerning alkene substrates are still lacking. Furthermore, in many cases it seems to be difficult to avoid overoxidation of the allylic alcohol to the corresponding enone. In addition, most published procedures utilize the alkene in a large excess (often as a solvent), thus limiting the use of functionalized alkenes which are not commercially available. 

W. Adam, V. R. Stegmann, C. R. Saha-Moller, Regio- and Diastereoselective epoxidation of chiral allylic alcohols catalyzed by manganese(salen) and iron (porphyrin) complexes, J. Am. Chem. Soc. 121 (1999) 1879. 

The Fe3(CO)i2-catalyzed isomerization of 3-ethyl-l-pentene-3di gives 3-ethyl-2-pentene in which the deuterim label is randomly scrambled among the three methyl groups without loss of deuterium . The recovered 1-olefin also shows rapid random scrambling. These experiments demonstrate the intermediacy of w-allyl iron carbonyl hydrides and indicate Aat multiple addition-eliminations proceed before decomplexation of the catalyst occurs as... 

Plietker B (2006) A highly regioselective salt-free iron-catalyzed allylic alkylation. Angew Cbem Int Ed 45 1469-1473... 

Plietker B, Dieskau A, Moews K, Jatsch A (2008) Ligand-dependent mechanistic dichotomy in iron-catalyzed allylic substitutions sigma-allyl versus pi-allyl mechanism. Angew Cbem Int Ed 47 198-201... 

Scheme 12.73 Iron-catalyzed alkoxy allylation of activated double bonds [158].

Scheme 12.75 Iron-catalyzed allylation/isomerization of double bonds [172]. 12.3.3...

Paradine SM, White MC. Iron-catalyzed intramolecular allylic C-H amination. J Am Chem Soc. 2012 134 2036-2039. 

The first example of an allylic alkylation catalyzed by iron compounds was reported in 1979. Allylic halides and carboxylates are treated with a diethyl malonate anion in the presence of sodium tricarbonyl(nitrosyl)ferrate to give the allylated malonates with good regioselectivity in favor of the ipso product (Scheme 4-195). This transformation can be carried out in a carbon monoxide atmosphere catalyzed by the Hieber-type complex [Bu4N][Fe(CO)3NO] (TBAFe) that is easier to handle. The... 

Scheme 4-197. Postulated o-allyl mechanism for the iron-catalyzed...

Scheme 4-200. Examples for an iron-catalyzed N2-type reaction of allyl phosphates with Grignard reagents.

In addition to the cross-coupling reactions of alkyl halides or sulfonates with organometallic nucleophiles, the former can also directly undergo C-C bond formation with nonactivated C-H bonds of alkenes or arenes in a Heck-type reaction. Iron-catalyzed intramolecular dehydrohalogenation of 2-iodoethanal alkenyl acetals with phenyl-magnesium bromide in the presence of a catalytic amount of iron(II) chloride provides tetrahydrofliran derivatives in moderate yields (Scheme 4-240). Allyl 2-halophenyl ethers provide dihydrobenzofiiran derivatives under these conditions. ... 

The iron-catalyzed isomerization of allylic alcohols can be combined with addition of aldehydes in a one-step procedure to give the corresponding aldol products (Scheme 4-293). Efficient iron catalysts for this transformation are pentacarbonyliron [Fe(CO)5], (tricarbonyl)(benzylideneaceton)iron [(dba)Fe(CO)3], or (tri-carbonyl)(cyclooctatetraene)iron [(cot)Fe(CO)3]. ... 

Allylic ethers may react with 2,3-disubstituted 1,3-butadienes in an iron-catalyzed process in two different modes depending on the ligand (Scheme 4-312). A [4+4] ene reaction is favored when a bipyridine(diene)iron complex is used as catalyst to form the corresponding vinyl ethers. If l,2-bis(diphenylphosphano)ethane is used as ligand, a 1,4-hydrovinylation of the diene is observed. The active Fe(0) catalysts are synthesized from Fe(ll) or Fe(III) salts by reduction with Grignard or trialkylaluminum reagents. ... 

Synthesis of (A) started with the combination of 2,4,6-trimethylphenol and allyl bromide to give the or/Ao-allyl dienone. Acid-catalyzed rearrangement and oxidative bydroboration yielded the dienone with a propanol group in porlactone ring were irons in the product as expected (see p. 275). Treatment with aqueous potassium hydroxide gave the epoxy acid, which formed a crystalline salt with (R)-l-(or-naphthyl)ethylamine. This was recrystallized to constant rotation. 

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