Categories: C-O Bond Formation >
Synthesis of Phenols
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Name Reactions
Sandmeyer-type Reaction
Recent Literature
The direct and selective palladium-catalyzed synthesis of phenols from aryl
halides and KOH has been achieved through the use of highly active
monophosphine-based catalysts and the biphasic solvent system 1,4-dioxane/H2O.
K. W. Anderson, T. Ikawa, R. E. Tundel, S. L. Buchwald, J. Am. Chem. Soc., 2006,
128, 10694-10695.
CuI-nanoparticles catalyze a selective synthesis of phenols, anilines, and
thiophenols from aryl halides in the absence of both ligands and organic
solvents. Anilines were formed selectively with ammonia competing with
hydroxylation and thiophenols were generated selectively with sulfur powder
after subsequent reduction competing with hydroxylation and amination.
H.-J. Xu, Y.-F. Liang, Z.-Y. Cai, H.-X. Qi, C.-Y. Yang, Y.-S. Feng, J. Org. Chem., 2011,
76, 2296-2300.
A CuI/8-hydroxyquinoline-catalyzed direct hydroxylation of aryl iodides with KOH
takes place at 100˚C in a mixed solvent system providing a broad range of
phenols. Aryl bromides are less reactive under these reaction conditions.
S. Maurer, W. Liu, X. Zhang, Y. Jiang, D. Ma, Synlett, 2010,
976-978.
The use of Oxone allows the conversion of various aryl-, heteroaryl-, alkenyl-,
and alkyltrifluoroborates into the corresponding oxidized products in excellent
yields. This method tolerates a broad range of functional groups, and in
secondary alkyl substrates it was demonstrated to be completely stereospecific.
G. A. Molander, L. N. Cavalcanti, J. Org. Chem., 2011,
76, 623-630.
A general and efficient copper-catalyzed oxidative hydroxylation of arylboronic
acids at room temperature in water gives phenols in excellent yields.
J. Xu, X. Wang, C. Shao, D. Su, G. Cheng, Y. Hu, Org. Lett., 2010,
12, 1964-1967.
For a selective hydroxylation of aryl iodides and aryl bromides with
tetrabutylammonium hydroxide pentahydrate, a combination of copper(I) iodide and
8-hydroxyquinaldine in a mixture of dimethyl sulfoxide and water is used. The
resulting phenols can be readily reacted with alkyl and allyl halides in situ to
provide the corresponding alkyl or allyl aryl ethers in high yields.
R. Paul, M. A. Ali, T. Punniyamurthy, Synthesis, 2010,
4268-4272.
A Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids with
arylboronic acids is a facile and practical methodology to access phenolic
esters in good yields. The procedure tolerates various functional groups, such
as methoxycarbonyl, acetoxy, free phenolic hydroxyl, vinyl, nitro,
trifluoromethyl, methoxyl, bromo, chloro, iodo, and acetyl groups.
L. Zhang, G. Zhang, M. Zhang, J. Cheng, J. Org. Chem., 2010,
75, 7472-7474.
Various siletanes have been used as substrates for the oxidation of
carbon-silicon bonds upon exposure to aqueous fluoride and peroxide. These
tetraalkylsilanes offer a combination of stability and reactivity with many
practical benefits, including compatibility with silicon protecting groups
and electron-rich aromatic rings.
J. D. Sunderhaus, H. Lam, G. B. Dudley, Org. Lett.,
2003,
8, 4571-4573.
Pd(II)-catalyzed ortho-hydroxylation of variously substituted benzoic acids
under an athmospheric pressure of oxygen or air is achieved under nonacidic
conditions. Labeling studies support a direct oxygenation of aryl C-H
bonds with molecular oxygen.
Y.-H. Zhang, J.-Q. Yu, J. Am. Chem. Soc., 2009,
131, 14654-14655.
Nitroarenes react with anions of tert-butyl and cumyl
hydroperoxides in the presence of strong bases to form substituted o- and
p-nitrophenols. The reaction usually proceeds in high yields and is of
practical value as a method of synthesis and manufacturing of nitrophenols.
M. Makosza, K. Sienkiewicz, J. Org. Chem., 1998,
63, 4199-4208.
Various anilides have been directly ortho-acetoxylated with acetic acid as the acetate
source and K2S2O8 as the oxidant in the
presence of
Pd(OAc)2 as catalyst. The amide group is an elegant directing group to convert aromatic sp2 C-H bonds into C-O bonds.
G.-W. Wang, T.-T. Yuan, X.-L. Wu, J. Org. Chem., 2008,
73, 4717-4720.
A palladium-catalyzed synthesis of aryl tert-butyl ethers from a
variety of unactivated aryl bromides or chlorides is described. The ether
products, which are precursors to phenols, are obtained in very good yield
in the presence of air-stable dialkylphosphinobiphenyl ligands.
C. A. Parrish, S. L. Buchwald, J. Org. Chem, 2001,
66, 2498-2500.
Drawbacks associated with the classic Balz-Schiemann reaction are eliminated
in a series of examples by conducting fluorodediazoniation in ionic liquid
solvents.
K. K. Laali, V. J. Gettwert, J. Fluorine Chem., 2001,
107, 31-34.
