Categories: C-C Bond Formation > Arenes >
Allylic Substitution, Allylation
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Name Reactions
Aromatic Claisen Rearrangement
Recent Literature
The cross-coupling reaction of aryl and vinyl boronic acids and allylic
alcohols proceeded smoothly in toluene or dioxane in the presence of a
(triphenyl phosphite)palladium catalyst to give the corresponding
allylbenzene derivatives and 1,4-dienes. Neither cocatalysts for promoting
C-O bond cleavage of allylic alcohols nor bases for activation of
organoboron reagents are required.
Y. Kayaki, T. Koda, T. Ikariya, Eur. J. Org. Chem., 2004,
4989-4993.
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.
Functionalized diarylzinc reagents react readily with allylic chlorides or
phosphates in the presence of Co(acac)2 as catalyst to give the SN2
products in high yields and with retention of the double-bond configuration.
Functionalities such as ester, ketone, or cyano are tolerated.
G. Dunet, P. Knochel, Synlett, 2007,
1383-1386.
The use of Zn powder in the presence of LiCl in THF allows a simple,
high-yielding preparation of a broad range of functionalized aryl- and
heteroarylzinc reagents. The synthesis of alkylzinc reagents was performed
from inexpensive alkyl bromides.
A. Krasovski, V. Malakhov, A. Gavryushin, P. Knochel, Angew. Chem. Int. Ed., 2006,
45, 6040-6044.
The palladium-catalyzed reaction of allyl acetates with aryl- and
vinyltin reagents gave good yields of cross-coupled products. The reaction
was mild and tolerant of functionality (-CO2R, -OH, -OSiR3,
-OMe) in the tin reagent. Inversion of stereochemistry at the acetate center
was observed, with retention of the geometry of the olefin of the allyl
group and with exclusive coupling at the primary position. Retention of
geometry of the olefin in the vinyltin reagents was also observed.
L. Del Valle, J. K. Stille, L. S. Hegedus, J. Org. Chem, 1990,
55, 3019-3023.
Palladium-catalyzed coupling reactions of functionalized allylboronic acids
with various iodobenzenes under standard Suzuki-Miyaura coupling conditions
afforded selectively the branched allylic products in high to excellent
yields.
S. Sebelius, V. J. Olsson, O. A. Wallner, K J. Szabó, J. Am. Chem. Soc.,
2006,
128, 8150-8151.
S. Sebelius, V. J. Olsson, O. A. Wallner, K J. Szabó, J. Am. Chem. Soc.,
2006,
128, 8150-8151.
Silylated cyanohydrins of iodo-substituted aryl, heteroaryl, or cycloalkenyl
ketones undergo an I/Mg-exchange using i-PrMgCl·LiCl. After
subsequent reactions with electrophiles, a facile deprotection
produces polyfunctional ketones in good overall yiels. An extension to
aromatic iodoaldehydes is described.
C.-Y. Liu, H. Ren, P. Knochel, Org. Lett.,
2006,
8, 617-629.
Treatment of fluorapatite with an aqueous solution of RhCl3 resulted
in rhodium-exchanged fluorapatite catalyst (RhFAP), which successfully promoted
cross coupling of Baylis-Hillman adducts with a variety of arylboronic
acids to yield trisubstituted olefins in a highly stereoselective manner. RhFAP
was recovered quantitatively by simple filtration and reused with almost
consistent activity.
M. L. Kantam, K. B. S. Kumar, B. Sreedhar, J. Org. Chem., 2008,
73, 320-322.
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.
G. W. Kabalka, J. Org. Chem., 2005,
70, 9207-9210.
