Categories: C-C Bond Formation > Chains >
Synthesis of substituted alkenes
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Recent Literature
The use of 2% Pd2(dba)3/8% PCyp3/NMI in
THF/NMP at 80°C achieves the cross-coupling of a range of
β-hydrogen-containing primary alkyl iodides, bromides, chlorides, and
tosylates with an array of alkyl-, alkenyl-, and arylzinc halides. This
method tolerates various functional groups.
J. Zhou, G. C. Fu, J. Am. Chem. Soc.,
2003,
125, 12527-12530.
"Ligandless" palladium complexes can catalyze the zirconium-Negishi
reactions of alkyl electrophiles. Ligandless processes offer low cost,
simplicity, and ease of purification.
S. L. Wiskur, A. Korte, G. C. Fu, J. Am. Chem. Soc.,
2004,
126, 82-83.
In the presence of Co(PPh3)2I2, PPh3,
water, and zinc powder, the reductive coupling of alkynes with alkenes
having an electron-withdrawing substituent proceeded smoothly in
acetonitrile to give the corresponding reductive coupling products in fair
to excellent yields. Possible mechanisms for this highly regio- and
stereoselective ene-yne reaction are proposed.
C.-C. Wang, P.-S. Lin, C.-H. Cheng, J. Am. Chem. Soc., 2002,
124, 9696-9697.
Use of a zirconocene catalyst based on the Brintzinger ligand and catalytic
amounts of methyl aluminoxanes (MAO) effect a >99% regiocontrol of Negishi
carboaluminations of 1-alkynes in toluene.
B. H. Lipshutz, T. Butler, A. Lower, J. Am. Chem. Soc., 2006,
128, 15396-15398.
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.
An easy access to (Z)-trisubstituted allylic alcohols is based on
E to Z isomerization of 1-bromo-1-dialkylvinylboranes upon
reaction with dialkylzinc reagents. Subsequent transmetalation to give (Z)-trisubstituted
vinylzinc species is followed by trapping with aldehydes to furnish a series
of (Z)-trisubstituted allylic alcohols.
Y. K. Chen, P. J. Walsh, J. Am. Chem. Soc.,
2004,
126, 3702-3703.
The use of bisphosphine ligands with a large P-Pd-P bite angle allowed to
synthesize Z-chlorinated internal alkenes in good yields by a selective
Suzuki-Miyaura monocoupling process of 9-alkyl-9-BBN with
1,1-dichloro-1-alkenes. These monochlorinated olefins could be further
transformed providing stereospecifically trisubstituted olefins.
F. Liron, C. Fosse, A. Pernolet, E. Roulland, J. Org. Chem., 2007,
72, 2220-2223.
A radical alkenylation reaction of α-halo carbonyl compounds with
styrylindium dichloride as well as unactivated alkenylindiums proceeded in
the presence of triethylborane. The geometry of the carbon-carbon double
bonds was retained. Efficient one-pot strategies were developed.
K. Takami, H. Yorimitsu, K. Oshima, Org. Lett.,
2004,
6, 4555-4558.
An additive-free, clean conjugate addition reaction of organosiloxanes to α,β-unsaturated
compounds is catalyzed by a cationic rhodium complex in dioxane/water. The
mechanism involves a transmetalation step between the rhodium complex and the
silicon reagent.
S. Oi, Y. Honma, Y. Inoue, Org. Lett., 2002,
4, 667-669.
Conjugate addition of dimethyl alkenylboronates to α,β-unsaturated ketones in the presence of catalytic amounts of 3,3'-disubstituted binaphthols provides alkenylation products in good yields and
high enantioselectivities.
T. R. Wu, J. M. Chong, J. Am. Chem. Soc., 2007,
129, 4908-4909.
A conjugate addition of organosiloxanes to α,β-unsaturated carbonyl
compounds catalyzed by a cationic rhodium complex generated from [Rh(cod)(MeCN)2]BF4
and (S)-BINAP in dioxane/water gave products in good yields and excellent
enantioselectivities.
S. Oi, A. Taira, Y. Honma, Y. Inoue, Org. Lett.,
2003, 5, 97-99.
Treatment of 2,2-dimethylpropan-1,3-diol esters of aryl- and alkenylboronic
acids with a catalytic amount of [Rh(OH)(cod)]2 in the presence
of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60°C under carbon
dioxide atmosphere gave carboxylic acids in good yields.
K. Ukai, M. Aoki, J. Takaya, N. Iwasawa, J. Am. Chem. Soc.,
2006,
128, 8706-8707.
On exposure to BuLi, 3-bromo-2-iodocyclopent-2-enol O-TBS ether
undergoes iodine-lithium permutation with complete regioselectivity.
Reaction with different electrophiles affords the corresponding
2-substituted-3-bromocyclopentenol derivatives. Subsequent bromo-lithium
exchange with t-BuLi, followed by reaction with an equal or different
electrophile, affords 2,3-disubstituted cyclopentenols.
M. Luparia, A. Vadalà, G. Zanoni, G. Vidari, Org. Lett.,
2006,
8, 2147-2150.
Opening of the epoxide ring of enantiopure (2R,1'S)-2-(1-aminoalkyl)epoxides
with different organolithium compounds gave allylamines with total
selectivity and in high yields.
J. M. Concellon, J. R. Suarez, V. del Solar, Org. Lett.,
2006,
8, 349-351.
