Categories: C-C Bond Formation > Oxygen-, Nitrogen-containing molecules > Active methylenes >
Benzylations
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Recent Literature
A palladium complex generated in situ from [Pd(η3-C3H5)(cod)]BF4
and DPPF is a good catalyst for benzylations of malonates with a wide range
of benzyl methyl carbonates. The DPEphos ligand is superior to DPPF in the
case of palladium-catalyzed benzylic amination of benzylic esters.
R. Kuwano, Y. Kondo, Y. Matuyama, J. Am. Chem. Soc.,
2003,
125, 12104-12105.
The reaction of 1,3-diketones, ketoesters, and ketoamides under non-anhydrous
conditions with substituted 1-phenylethanols gave benzylated products in high
yields in the presence of rare earth metal and hafnium triflates as catalysts.
The allylation of a diketone with allylic alcohols was also possible. Catalysts
can be recovered by water extraction and reused up to five times.
M. Noji, Y. Konno, K. Ishii, J. Org. Chem., 2007,
72, 5161-5167.
An efficient bismuth-catalyzed hydroalkylation of various styrenes,
norbornene, and cyclohexadiene with 1,3-dicarbonyl compounds provides the
corresponding alkylated pentanediones in good yields after short reaction
times.
M. Rüping, B. J. Nachtsheim, A. Künkel, Synlett, 2007,
1391-1394.
A highly effective bismuth-catalyzed benzylation and allylic alkylation of
2,4-pentanediones with free alcohols provides the corresponding monoalkylated
dicarbonyl compounds in high yields after short reaction times. In addition, a new route to
substituted indenes is presented.
M. Rüping, B. J. Nachtsheim, A. Künkel, Org. Lett., 2007,
9, 825-828.
A mild and direct indium-catalyzed process for the C-C bond formation from
alcohols and active methylenes, alkoxyketones or indoles was developed.
M. Yasuda, T. Somyo, A. Baba, Angew. Chem. Int. Ed., 2006,
45, 793-794.
A powerful one-pot method for the reductive alkylation of stoichiometric amounts
of malononitrile with aromatic aldehydes incorporates water as the catalyst in
ethanol for the condensation step. The subsequent reduction step takes place
quickly and efficiently with sodium borohydride to give monosubstituted
malononitriles.
F. Tayyari, D. E. Wood, P. E. Fanwick, R. E. Sammelson, Synthesis, 2008,
279-285.
A highly enantioselective catalytic alkylation of cyanoacetates was
achieved using a chiral phase-transfer catalyst to give α,α-disubstituted
α-cyanoacetates which have a chiral quaternary carbon.
K. Nagata, D. Sano, T. Itoh, Synlett, 2007, 547-550.
F. Stauffer, R. Neier, Org. Lett., 2000, 2, 3535-3537.
The synthesis and properties of different planar chiral
1-phosphino-2-sulfenylferrocene ligands are reported. Very high
enantioselectivities were obtained in the palladium-catalyzed allylic
substitution of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate (ee's
up to 97%) and nitrogen nucleophiles (ee's up to 99.5%) using the readily
available tert-butylsulfenyl derivatives.
O. G. Mancheno, J. Priego, S. Cabrera, R. G. Arrayas, T. Llamas, J. C.
Carretero, J. Org. Chem., 2003, 68, 3679-3686.
A series of trialkylsilylated chiral aminophosphine ligands are prepared
from (S)-prolinol and applied to a palladium-catalyzed asymmetric
allylic alkylation of 1,3-diphenyl-2-propenyl acetate with a dimethyl
malonate-BSA-LiOAc system.
Y. Tanaka, T. Mino, K. Akita, M. Sakamoto, T. Fujita, J. Org. Chem.,
2004,
69, 6679-6687.
Bis-pyridylamides were used in a regioselective Molybdenium-catalyzed
asymmetric allylation of carbonates. 4-substituted pyridyl ligands exhibited
high regioselectivity and enantioselectivity, whereas 6-substituted ligands
afforded no product under the same conditions.
O. Belda, C. Moberg, Synthesis,
2002, 1601-1603.
