Categories: C-C Bond Formation > Arenes >
α-Arylation
Recent Literature
A palladium-catalyzed coupling of aryl halides and ester enolates produced
α-aryl esters in high yields at room temperature. The reaction was highly
tolerant of functionalities and substitution patterns on the aryl halide.
Improved protocols for the selective monoarylation of tert-butyl
acetate and the efficient arylation of α,α-disubstituted esters were
developed with LiNCy2 as base and P(t-Bu)3 as ligand.
M. Jørgensen, S. Lee, X. Liu, J. P. Wolkowski, J. F. Hartwig, J. Am. Chem. Soc., 2002,
124, 12557-12565.
The complex (IPr)Pd(acac)Cl has proven to be a highly active PdII
precatalyst in Buchwald-Hartwig reactions and α-ketone arylations of a wide
range of substrates including unactivated, sterically
hindered, and heterocyclic aryl chlorides.
N. Marion, E. C. Ecarnot, O. Navarro, D. Amoroso, A. Bell, S. P. Nolan, J. Org. Chem., 2006,
71, 3816-3821.
2-aryl-1,3-dicarbonyl compounds are produced in good yields by a CuI/L-proline-catalyzed
arylation of activated methylene compounds with aryl iodides and aryl
bromides in DMSO at 40-50°C in the presence of Cs2CO3.
X. Xie, G. Cai, D. Ma, Org. Lett.,
2005,
7, 4693-4695.
A general method for the Suzuki-Miyaura and
carbonyl enolate coupling of unactivated arenesulfonates was developed
utilizing Pd(OAc)2 and XPhos as ligand. The catalyst system effects
the coupling of various aryl, heteroaryl, and extremely hindered arylboronic acids
and carbonyl enolates with
different aryl tosylates, under mild conditions.
H. N. Nguyen, X. Huang, S. L. Buchwald, J. Am. Chem. Soc., 2003,
125, 11818-11819.
The use of zinc enolates (isolated Reformatsky reagents or generated in situ
from α-bromo amides or lithium enolates) instead of alkali metal enolates,
greatly expands the scope of the palladium-catalyzed α-arylation of aryl
bromides and vinyl bromides.
T. Hama, D. A. Culkin, J. F. Hartwig, J. Am. Chem. Soc.,
2006,
128, 4976-4985.
The coupling of aryl iodides and diethyl malonate in the presence of Cs2CO3 and catalytic amounts of CuI and 2-phenylphenol gave α-aryl malonates in good to excellent yields. This mild method tolerates various functional groups.
E. J. Hennessy, S. L. Buchwald, Org. Lett., 2002, 4, 269-272.
A general method for the direct
α-arylation of nitriles with aryl chlorides was developed. With a
catalytic system of Pd and a commercially available ligand, it is now
possible to effect direct α-arylation using a wide variety of starting
materials.
J. You, J. G. Verkade, Angew. Chem., 2003,
115, 5205-5207.
A palladium-catalyzed α-arylation of nitriles was developed by exploring the structure and reactivity of arylpalladium cyanoalkyl complexes. The high yields and short reaction times observed for BINAP-ligated complexes suggested that BINAP-ligated palladium catalysts might be appropriate for the arylation of nitriles. Initial results on a palladium-catalyzed process for the direct coupling of aryl bromides and primary, benzylic, and secondary nitrile anions to form α-aryl nitriles in good yields are reported.
D. A. Culkin, J. F. Hartwig, J. Am. Chem. Soc., 2002,
124, 9330-9331.
Palladium-N-heterocyclic carbene (NHC) complexes were found to be
active catalysts for the arylation of various ketones with aryl chlorides,
bromides, and triflates in short reaction times.
M. S. Viciu, R. F. Germaneau, S. P. Nolan., Org.
Lett., 2002, 4, 4053-4056.
A convenient method has been developed for the palladium-catalyzed arylation of
malononitrile in high yields with aryl bromides and chlorides, respectively. The
influence of several reaction parameters such as base, ligand, solvent or
temperature were investigated.
A. Schnyder, A. F. Indolese, T. Maetzke, J. Wenger, H.-U. Blaser, Synlett, 2006,
3167-3168.
An efficient, mild, and general method for the C-arylation of β-enamino
esters and ketones with arynes provides a facile and direct access to various
substituted aromatic β-enamino compounds in good yield.
Y. K. Ramtohul, A. Chartrand, Org. Lett., 2007,
9, 1029-1032.
A very simple method for the α-arylation of N-protected
2-piperidinones in high yield is described. Key factors are the use of ZnCl2 and
Pd(dba)2 and the nature of the base.
A. de Filippis, D. G. Pardo, J. Cossy, Tetrahedron, 2004,
60,
9757-9767.
A small library of α,β-unsaturated oxindoles was prepared.
A. Teichert, K. Jantos, K. Harms, A. Studer, Org. Lett., 2004,
6, 3477-3480.
Novel chiral phosphine-olefin ligands have been designed, which acts as
bidentate in an efficient rhodium-catalyzed asymmetric 1,4-addition of aryl
boronic acids to maleimides.
R. Shintani, W.-L. Duan, T. Nagano, A. Okada, T. Hayashi, Angew. Chem., 2005,
117, 4687-4690.
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Palladium-catalyzed
alpha-Arylation of Esters, Ketones, Amides and Imides |
