Categories: C-C Bond Formation > Chains > Alkynes >
Synthesis of substituted 1,3-enynes
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Recent Literature
The cross-coupling reaction of (E)- and (Z)-alk-1-enyldialkylborane
with (trimethylsilyl)ethynyl bromide proceeds in the presence of a catalytic
amount of copper(II) acetylacetonate and a base under extremely mild
conditions to provide conjugated enynes with a distal carbon-carbon triple
bond.
M. Hoshi, N. Kawamura, K. Shirakawa,
Synthesis, 2006, 1961-1970.
Cross-coupling of 1-alkynes with vinyl iodides catalyzed by CuI/N,N-dimethylglycine
affords conjugated enynes in good to excellent yields. Heating a mixture of
2-bromotrifluoroacetanilide, 1-alkyne in the presence of CuI/L-proline
leads to the formation of the corresponding indole.
F. Liu, D. Ma, J. Org. Chem., 2007,
72, 4844-4850.
A palladium(II) complex based on N,N-dimethylethanolamine can be used as
a catalyst in copper-free Sonogashira couplings of (E)- or (Z)-bromostyrenes
with alkynes to produce conjugated enynes at room temperature in good yields
with retention of the configuration.
X. Mi, M. Huang, Y. Feng, Y. Wu, Synlett, 2012,
1257-1261.
A copper(I)-catalyzed coupling of alkynes with vinyl iodides affords various enynes in good to excellent yields, tolerates a
variety of functional groups, and does not require the use of expensive additives.
C. G. Bates, P. Saejueng, D. Venkataraman, Org. Lett., 2004,
6, 1441-1444.
Multifunctional palladium catalysis allows a one-pot stereocontrolled synthesis
of tetrasubstituted methyl ketones and enynes. The homogeneous palladium
dihalide catalyst is used
for the bromo-/chloroallylation of alkynes and in situ for subsequent
Wacker-Tsuji oxidation or Sonogashira cross-coupling.
A. N. Thadani, V. H. Rawal, Org. Lett., 2002, 4,
4321-4323.
Alkynyl Grignard reagents, prepared from the corresponding alkynes and
methylmagnesium bromide, react with alkenyl bromides or triflates in the
presence of FeCl3 as catalyst and lithium bromide as additive to give
the corresponding conjugated enynes in high to excellent yields. The reaction
shows wide applicability to various terminal alkynes and alkenyl electrophiles.
T. Hatakeyama, Y. Yoshimoto, T. Gabriel, M. Nakamura, Org. Lett., 2008,
10, 5341-5344.
A simple procedure for the synthesis of substituted (E)-2-alkene-4-ynecarboxylic
esters has been achieved using hydroxyapatite-supported palladium as efficient
catalyst surface. The highly efficient catalyst can be recycled.
B. C. Ranu, L. Adak, K. Chattopadhyay, J. Org. Chem., 2008,
73, 5609-5612.
An efficient, palladium-catalyzed synthesis of 2-alkene-4-ynoates and -nitriles
by a simple reaction of vic-diiodo-(E)-alkenes with acrylic esters
and nitriles in water leads to (E)-isomers from acrylic esters
exclusively, whereas (Z)-isomers are obtained in high stereoselectivity from
reactions of acrylonitrile. The in situ prepared Pd(0) nanoparticles can be
recycled.
B. C. Ranu, K. Chattopadhyay, Org. Lett., 2007,
9, 2409-2412.
B. C. Ranu, K. Chattopadhyay, Org. Lett., 2007,
9, 2409-2412.
A straightforward one-pot approach to highly diverse conjugated enynes,
starting from carbonyl precursors has been developed. The low nucleophilic
phosphazene bases, which are used for the generation of the alkenyl
nonaflates and the terminal alkynes, are compatible with NfF and do not
impede the subsequent Sonogashira reaction.
I. M. Lyapkalo, M. A. K. Vogel, Angew. Chem. Int. Ed., 2006,
45, 4019-4023.
An efficient synthesis of structurally diverse fused furans in good yields from
2-alkynylcycloalk-2-enols via gold(III) bromide catalyzed cycloisomerization
was achieved under moderate reaction conditions.
C. Praveen, P. Kiruthiga, P. T. Perumal, Synlett, 2009,
1990-1996.
2-Alkynyl esters are stereo- and regioselectively converted to E-β-chloro-α-iodo-α,β-unsaturated
esters by exposure to Bu4NI in refluxing dichloroethane.
Single-isomer tetrasubstituted olefins bearing four different carbon
substituents are then synthesized by sequential palladium-catalyzed coupling
reactions.
A. B. Lemay, K. S. Vulic, W. W. Ogilvie, J. Org. Chem., 2006,
71, 3615-3618.
Dinuclear and mononuclear palladium complexes with N,N'-bis[2-(diphenylphosphino)phenyl]amidinate
(DPFAM) as a ligand catalyzed the cross-addition of triisopropylsilylacetylene (TIPSA)
to unactivated internal alkynes, giving enynes selectively. The reactions of
TIPSA with several terminal alkynes also gave cross-adducts selectively,
although the yields were moderate.
N. Tsukada, S. Ninomiya, Y. Aoyama, Y. Inoue, Org. Lett., 2007,
9, 2919-2921.
Alkynylboration of alkynes with alkynyl(pinacol)boranes in the presence of
nickel catalysts gave cis-1-borylbut-1-en-3-yne derivatives. Some
boryl-substituted enynes were reacted with sp2 halides under
Suzuki-Miyaura coupling conditions.
M. Suginome, M. Shirakura, A. Yamamoto, J. Am. Chem. Soc., 2006,
128, 14438-14439.
