Categories: C-C Bond Formation > Alcohols, Arenes >
Synthesis of benzylic alcohols
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Chiral amino thioacetate ligands were remarkably superior to the corresponding
amino alcohols as catalysts for enantioselective aryl transfer reactions. Low
catalyst loadings were sufficient to achieve excellent enantioselectivity as
well as high conversion in short reaction time.
M.-J. Jin, S. M. Sarkar, D.-H. Lee, H. Qiu, Org. Lett., 2008,
10, 1235-1237.
The value of stable and easily accessible triarylborane ammonia complexes as
precursors for arylzinc reagents in asymmetric catalysis is demonstrated.
Various chiral diarylmethanols were synthesized in high yield and
enantioselectivity.
S. Dahmen, M. Lormann, Org. Lett.,
2005,
7, 4597-4600.
Enantiomerically enriched diarylmethanols have been prepared by catalyzed
asymmetric phenyl transfer reactions onto aromatic aldehydes with use of readily
available β-hydroxysulfoximines as catalysts. Various functionalized aldehydes
and heterocyclic substrates are tolerated, yielding synthetically relevant
products.
J. Sedelmeier, C. Bolm, J. Org. Chem., 2007,
72, 8859-8862.
An efficient new methodology for the arylation of aldehydes is disclosed which
uses dirhodium(II) catalysts and N-heterocyclic carbene (NHC) ligands. An
N-heterocyclic carbene monocomplex of dirhodium(II) acetate was shown to
be the most active catalyst and was particularly efficient in the arylation of
alkyl aldehydes.
A. F. Trindade, P. M. P. Gois, L. F. Veiros, V. André, M. T. Duarte, C. A. M.
Afonso, S. Caddick, F. G. N. Cloke, J. Org. Chem., 2008,
73, 4076-4086.
The use of a thioether-imidazolinium chloride as a heterobidentate carbene
ligand precursor led to a high level of catalyst performance in the
palladium-catalyzed 1,2-addition of aryl-, heteroaryl-, and alkenylboronic acids
to aromatic, heteroaromatic, and aliphatic aldehydes.
M. Kuriyama, R. Shimazawa, R. Shirai, J. Org. Chem., 2008,
73, 1597-1600.
The 1,2-addition of aryl- or heteroarylboronic acids to aldehydes in the
presence of PdCl2 and P(1-Nap)3 affords carbinol
derivatives in very good yields. The reaction tolerates nitro, cyano, acetamido,
acetoxy, acetyl, carboxyl, trifluoromethyl, fluoro, and chloro groups and allows
the conversion of aliphatic aldehydes and hindered substrates.
C. Qin, H. Wu, J. Cheng, X. Chen, M. Liu, W. Zhang, W. Su, J. Ding, J. Org. Chem., 2007,
72, 4102-4107.
Anionic four-electron donor-based palladacycles were highly efficient,
practical catalysts for 1,4-additions of arylboronic acids with α,β-unsaturated
ketones and 1,2-additions of arylboronic acids with aldehydes and α-ketoesters.
P. He, Y. Lu, C.-G. Dong, Q.-S. Hu, Org. Lett., 2007,
9, 343-346.
Cationic Pd(II) complex-catalyzed addition of arylboronic acids to aldehydes
gave diarylmethanols in high yields with low catalyst loading. A one-pot
synthesis of unsymmetrical triarylmethanes from arylboronic acids, aryl
aldehydes, and electron-rich arenes was achieved in high yields.
S. Lin, X. Lu, J. Org. Chem., 2007,
72, 9757-9760.
Aldehydes and siloxanes form methyl esters in a single step through mild
oxidative esterification in the presence of a palladium catalyst or,
alternatively, afford secondary alcohols via TBAF-promoted arylation in the
absence of a catalyst at increased temperatures.
R. Lerebours, C. Wolf, J. Am. Chem. Soc., 2006,
128, 13052-13053.
A H8-binol derived catalyst allows high enantioselectivity in the
reaction of diphenylzinc with both aliphatic and aromatic aldehydes. The use
of this catalyst avoids the need for additives such as diethylzinc and the
mild asymmetric reaction conditions make this chiral catalyst useful for
general synthesis.
Y.-C. Qin, L. Pu, Angew. Chem. Int. Ed., 2006,
45, 273-277.
In a highly efficient enantioselective organozinc addition to ketones, chiral
phosphoramide-Zn(II) complexes serve as conjugate Lewis acid-Lewis base
catalysts. From a variety of nonactivated aromatic and aliphatic ketones, the
corresponding optically active tertiary alcohols were obtained in high yields
with high enantioselectivities under mild reaction conditions.
M. Hatano, T. Miyamoto, K. Ishihara, Org. Lett., 2007,
9, 4535-4538.
The asymmetric addition of phenyl groups from diphenylzinc to ketones
gives good to excellent enantioselectivity with a range of substrates, using
a catalyst generated from a dihydroxy bis(sulfonamide) ligand and titanium
tetraisopropoxide.
C. Garcia, P. J. Walsh, Org. Lett., 2003,
5, 3641-3644.
A palladium(0) complex with chloroform is able to catalyze the addition of
arylboronic acids to aldehydes in the presence of a base, affording the
corresponding secondary alcohols in good yields. A catalytic amount of
chloroform seems to be essential for this reaction.
T. Yamamoto, T. Ohta, Y. Ito, Org. Lett.,
2005,
7, 4151-4155.
Kinetic vs thermodynamic deprotonation studies on secondary and tertiary
sulfonamides using n-BuLi have been carried out. Application of the
developed conditions allows the synthesis of diverse sulfonamide products
(E=CH(OH)Ph).
S. L. MacNeil, O. B. Familoni, V. Snieckus, J. Org. Chem, 2001,
66, 3662-3670.
Various N-acylethylenediamine-based ligands were screened as
catalysts for the asymmetric addition of vinylzinc reagents to aldehydes.
The optimized ligand was found to catalyze the formation of (E)-allylic
alcohols with high enantioselectivities for both aromatic and α-branched
aldehydes, and vinylzinc reagents derived from both bulky and straight chain
terminal alkynes.
C. M. Sprout, M. L. Richmond, C. T. Seto, J. Org. Chem., 2005,
70, 7408-7417.
The asymmetric Friedel-Crafts reaction of N,N-dialkylanilines with
ethyl glyoxylate has been achieved by the catalysis of titanium complexes of
BINOL derivatives to give the corresponding mandelic acid ethyl esters in
high yields (85-99%) and good to excellent enantioselectivity (80-96.6% ee).
Y. Yuan, X. Wang, X. Li, K. Ding, J. Org. Chem.,
2004, 69, 146-149.
