Iron (low valent)
Recent Literature
Fe(0) is cost-effective, environmentally friendly alternative to Cr(II) for
the olefination of carbonyls by activated polyhalides. Fe(0) proved
compatible with a wide range of functionality, such as unprotected phenol,
aryl nitro, carboxylic acid, and alkyl nitrile.
J. R. Falck, R. Bejot, D. K. Barma, A. Bandyopadhyay, S. Joseph, C. Mioskowski, J. Org. Chem., 2006, 71, 8178-8182.
An operationally simple and very efficient Reformatsky reaction of aldehydes has
been carried out in THF in the presence of low valent iron or copper which were
prepared in situ employing a bimetal redox strategy through reduction of Fe(III)
or Cu(II) salts with magnesium.
A. Chattopadhyay, A. Kr. Dubey, J. Org. Chem., 2007,
72, 9357-9359.
An efficient, economical, and practical Reformatsky reaction of α-halo esters
with carbonyl compounds is mediated by cheap iron(0) powder. The reactions
proceeded effectively in the presence of a catalytic amount of iodine to afford
synthetically useful β-hydroxyl carbonyl compounds in good yields.
X.-Y. Liu, X.-R. Li, C. Zhang X.-Q. Chu, W. Rao, T.-P. Loh, Z.-L. Shen,
Org. Lett., 2019, 21, 5873-5878.
An iron complex containing electronically coupled acidic and hydridic hydrogens
catalyzes the hydrogenation of ketones under mild conditions and shows high
chemoselectivity for aldehydes, ketones, and imines. Isolated carbon double and
triple bonds, aryl halides, nitrates, epoxides, and ester functions are
unaffected by the hydrogenation conditions.
C. P. Casey, H. Guan, J. Am. Chem. Soc., 2007,
129, 5816-5817.
For highly stereoselective reductions of a large number of five- and
six-membered cyclic ketones to the most thermodynamically stable alcohols,
ketones are treated with lithium dispersion and either FeCl2·4H2O
or CuCl2·2H2O in THF at room temperature. This protocol is
more convenient and efficient than those commonly reported for similar
reductions.
N. Kennedy, T. Cohen, J. Org. Chem.,
2015,
80, 8134-8141.
A facile and practical method for the synthesis of N-acetyl
α-arylenamides from the corresponding ketoximes with ferrous acetate as the
reducing reagent offers mild reaction conditions, simple purification procedures,
and high yields for a variety of N-acetyl enamides.
W. Tang, A. Capacci, M. Sarvestani, X. Wei, N. K. Yee, C. H. Senanayake, J. Org. Chem., 2009,
74, 9528-9530.
An intermolecular reductive Schiff base formation from nitroarenes and
benzaldehydes to yield diarylimines is carried out in the presence of iron
powder and dilute acid. This process tolerates various functional groups and
often proceeds quantitatively with no need for purification.
A. L. Korich, T. S. Hughes, Synlett, 2007,
2602-2604.
The very inexpensive carbonyl iron powder (CIP), a highly active commercial
grade of iron powder, enables an especially mild, safe, efficient, and
environmentally responsible reduction of aromatic and heteroaromatic nitro
groups in water. These reductions are conducted in a recyclable aqueous reaction
medium in the presence of nanomicelles composed of TPGS-750-M.
N. R. Lee, A. A. Bikovtseva, M. Cortes-Clerget, F. Gallou, B. H. Lipshutz, Org. Lett.,
2017, 19, 6518-6521.
An efficient Fe/CaCl2 system enables the reduction of nitroarenes and
reductive cleavage of azo compounds by catalytic transfer hydrogenation in the
presence of sensitive functional groups including halides, carbonyl, aldehyde,
acetyl, nitrile, and ester substituents with excellent yields. The simple
experimental procedure and easy purification make the protocol advantageous.
S. Chandrappa, T. Vinaya, T. Ramakrishnappa, K. S. Rangappa, Synlett, 2010,
3019-3022.
An efficient Fe/CaCl2 system enables the reduction of nitroarenes and
reductive cleavage of azo compounds by catalytic transfer hydrogenation in the
presence of sensitive functional groups including halides, carbonyl, aldehyde,
acetyl, nitrile, and ester substituents with excellent yields. The simple
experimental procedure and easy purification make the protocol advantageous.
S. Chandrappa, T. Vinaya, T. Ramakrishnappa, K. S. Rangappa, Synlett, 2010,
3019-3022.
A heterocycle-heterocycle interconversion strategy provides 4,5-disubstituted
3-hydroxy-2-pyrrolidinones in good yields. The reported reductive rearrangement approach
especially allows access to unsubstituted 3-hydroxy-2-pyrrolidinone at the
nitrogen position for further functionalization.
P. Kamath, V. Jadhav, M. Lal, Synlett, 2021,
32,
1146-1150.
Reduction of o-nitroarylcarbaldehydes o-aminoarylcarbaldehydes with iron
in the presence of a catalytic amount of aqueous hydrochloric acid followed by
in situ condensation of the resulting amines with ketones or aldehydes (Friedlaender
quinoline synthesis) gives mono- or disubstituted quinolines, respectively, in
very good yields.
A.-H. Li, D. J. Beard, H. Coate, A. Honda, M. Kadablbajoo, A. Kleinberg, R.
Laufer, K. M. Mulvihill, A. Nigro, P. Rastogi, M. W. Siu, A. G. Steinig, T.
Wang, D. Werner, A. P. Crew, M. J. Mulvihill, Synthesis, 2010,
1629-1632.
A tandem condensation of a cyanoimidate with an amine followed by reductive
cyclization in an iron-HCl system enables an efficient route to N4-substituted
2,4-diaminoquinazolines. An additional N-alkylation can produce two fused
heterocycles in a one-pot procedure.
P. Yin, N. Liu, Y.-X. Deng, Y. Chen, Y. Deng, L. He, J. Org. Chem., 2012,
77, 2649-2658.
Quinolines can be synthesized from Δ2-isoxazolines under
reductive conditions. The reductive cyclization to quinolines is achieved in the
presence of iron or sodium dithionite under metal-free conditions.
P. Kamath, R. C. Viner, S. C. Smith, M. Lal,
Synlett, 2017, 28, 1341-1345.