Categories: C-C Bond Formation > Arenes >
Benzylation, synthesis of diarylmethanes
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Recent Literature
A metal-free carbon-carbon bond-forming coupling between tosylhydrazones and
boronic acids is very general and functional-group tolerant. As the required
tosylhydrazones are easily generated from carbonyl compounds, it can be seen as
a reductive coupling of carbonyls, a process of high synthetic relevance that
requires several steps using other methodologies.
J. Barluenga, M. Tomás-Gamasa, F. Aznar, C. Valdés, Nat. Chem., 2009,
1, 494-499.
J. Barluenga, M. Tomás-Gamasa, F. Aznar, C. Valdés, Nat. Chem., 2009,
1, 494-499.
A novel InCl3/SiO2-catalyzed hydroarylation of various
styrenes with arenes can be carried out under solvent-free conditions to afford
a series of 1,1-diarylalkanes in high yields and with good regioselectivities.
The catalyst can be reused six times without obvious loss of catalytic activity.
G. Sun, H. Sun, Z. Wang, M.-M. Zhou, Synlett, 2008,
1096-1100.
A highly efficient secondary benzylation procedure of nucleophiles (arenes,
heteroarenes, alcohols, thiols, amides) with benzylic alcohols afforded the corresponding benzylated
products in moderate to excellent yields in the presence of a high-valent heterobimetallic complex [Ir2(COD)2(SnCl3)2(Cl)2(μ-Cl)2] as the catalyst.
S. Podder, J. Choudhury, S. Roy, J. Org. Chem., 2007,
72, 3129-3132.
The reaction of benzylic chlorides with Al-powder in the presence of InCl3
as catalyst provides various functionalized benzylic aluminum
sesquichlorides under mild conditions. These organometallics reacted smoothly in
Pd-catalyzed cross-couplings, or Cu-mediated acylations, allylations, or
1,4-addition reactions. Substrates prone to Wurtz coupling can be converted to
benzylic zinc compounds first.
T. D. Blümke, K. Gross, K. Karaghiosoff, P. Knochel, Org. Lett., 2011,
13, 6440-6443.
Diarylmethanes can be accessed efficiently by Suzuki-Miyaura cross-couplings of
arylboronic acids with benzyl halides mediated by trans-PdBr(N-Succ)(PPh3)2.
The methodology can be applied to the synthesis of heteroaryl analogues.
I. J. S. Fairlamb, P. Schnal, R. J. K. Taylor, Synthesis, 2009,
508-510.
The palladium-catalyzed cross-coupling of various benzylic carbonates with
arylboronic acids gave the corresponding diarylmethanes in high yields. The
catalyst is generated in situ from [Pd(η3-C3H5)Cl]2
and 1,5-bis(diphenylphosphino)pentane (dpppe).
R. Kuwano, M. Yokogi, Org. Lett., 2005,
7, 945-947.
A cross-coupling reaction of various aryl, heteroaryl, and benzyl chlorides with
ArMgX is catalyzed by nickel in the presence of a bidentate phosphine ligand.
The ligand is stable in air and forms a stable complex in situ upon reaction
with Ni(CH3CN)2Cl2.
R. Ghosh, A. Sarkar, J. Org. Chem., 2010,
75, 8283-8386.
The use of the Xantphos ligand in a mild palladium-catalyzed Kumada-Corriu
reaction of secondary benzylic bromides with aryl and alkenyl Grignard reagents
minimizes the undesired β-elimination pathway. The corresponding cross-coupling
products can be isolated in good yields with inversion of the configuration.
A. López-Pérez, J. Adrio, J. C. Carretero, Org. Lett., 2009,
11, 5514-5517.
An efficient Hiyama coupling reaction between benzylic halides and
aryltrialkoxysilanes using Pd nanoparticles allows the synthesis of a diverse
range of diarylmethanes which are ubiquitous units of natural products and
pharmaceuticals.
D. Srimani, A. Bej, A. Sarkar, J. Org. Chem., 2010,
75, 4296-4299.
Suzuki-Miyaura cross-coupling of benzylic phosphates with arylboronic acids
using a simple catalytic system of palladium(II) acetate and
triphenylphosphine with either potassium phosphate or potassium carbonate as
the base and toluene as the solvent at 90°C allows the preparation of a
series of structurally diverse diarylmethanes.
M. McLaughlin, Org. Lett.,
2005,
7, 4875-4878.
Coupling of sterically hindered aryl and activated alkyl chlorides bearing
β-hydrogens has been successfully achieved by using N-heterocyclic
carbene (NHC)Pd-carboxylate complexes as catalysts.
R. Singh, M. S. Viciu, N. Kramareva, O. Navarro, S. P. Nolan, Org. Lett.,
2005,
7, 1829-1832.
A new, reusable Pd/MgLa mixed oxide catalyst has been applied successfully
in the Suzuki-Miyaura cross-coupling reaction of aryl halides as well as
benzylic bromide with boronic acids in ethanol. The catalyst is air stable,
can be stored and handled under an ambient atmosphere and after the reaction
it can be recovered by simple filtration and reused without significant loss
of activity.
A. Cwik, Z. Hell, F. Figueras, Org. Biomol. Chem., 2005,
3, 4307-4309.
Palladium catalyzed Suzuki-Miyaura coupling with aryl chlorides using a
bulky phenanthryl N-heterocyclic carbene ligand
C. Song, Y. Ma, Q. Chai, C. Ma, W. Jiang, M. B. Andrus, Tetrahedron, 2005,
61, 7438-7446.
A combination of copper chloride, triethyl phosphite, and tetrabutylammonium
iodide is a very efficient catalytic system for cross-coupling reaction of
arylmagnesium halides with benzylic phosphates.
C. C. Kofink, P. Knochel, Org. Lett.,
2006,
8, 4121-4124.
A hybrid catalyst of iron oxide nanoparticles on carboxy-functionalized graphite
demonstrated superior catalytic activity towards the alkylation of arenes with
alkyl halides in contrast to commercial graphite or unsupported iron oxide
nanoparticles. The catalyst can be reused up to five times with a minimal loss
of catalytic activity.
V. Rajpara, S. Banerjee, G. Sereda, Synthesis, 2010,
2835-2840.
Suzuki-Miyaura coupling of diarylmethyl carbonates with arylboronic acids gives
various triarylmethanes in the presence of [Pd(η3-C3H5)Cl]2−DPPPent
(1,5-bis(diphenylphosphino)pentane) as catalyst.
J.-Y. Yu, R. Kuwano, Org. Lett., 2008,
10, 973-976.
Sm(OTf)3 is an effective catalysts for a versatile and efficient
halogen-promoted highly regio- and stereoselective Friedel-Crafts (F-C)
alkylation of electron-rich arenes with alkenes and α,β-unsaturated carbonyl
compounds in the presence of NBS or I2 as halogen sources.
S. Haira, B. Maji, S. Bar, Org. Lett., 2007,
9, 2783-2786.
The superacid-catalyzed reaction of various olefinic amines and
related compounds with benzene gives addition products in good yields. The
formation of reactive, dicationic electrophiles is proposed.
Y. Zhang, A. McElrea, G. V. Sanchez, Jr., D. Do, A. Gomez, S. L . Aguirre, R. Rendy, D. A. Klumpp, J. Org. Chem., 2003,
68, 5119-5122.
The reaction of different functionalised organolithium compounds prepared by
DTBB-catalysed lithiation of isochromane, phthalane, 2,3-dihydrobenzofuran
and 1-chloro-3,3-diethoxypropane with an equimolecular amount of zinc
bromide, followed by reaction with an aryl or an alkenyl bromide in the
presence of a palladium catalyst gives the expected cross-coupling products.
M. Yus, J. Gomis, Eur. J. Org. Chem., 2002, 1989-1995.
A palladium-catalyzed cross-coupling reaction between acetates of
Baylis-Hillman adducts and organosilanes in PEG as solvent is described.
G. W. Kabalka, J. Org. Chem., 2005,
70, 9207-9210.
