Categories: C-C Bond Formation > Chains > Alkynes >
Synthesis of substituted alkynes
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Recent Literature
Pd2(dba)3-Ph3P-catalyzed Kumada-Corriu
coupling reactions of unactivated alkyl bromides or iodides with alkynyllithiums
or the corresponding Grignard reagents furnish Csp-Csp3
bond formation. The superior
performance of Ph3P ligand over the trialkylphosphine ligands
indicates that this cross-coupling reaction may be a
reductive-elimination-controlled process.
L.-M. Yang, L.-F. Huang, T.-Y. Luh, Org. Lett., 2004, 6,
1461-1463.
A Pd/N-heterocyclic carbene-based catalyst achieves the Sonogashira
coupling of an array of functionalized, β-hydrogen-containing alkyl bromides
and iodides under mild conditions.
M. Eckhardt, G. C. Fu, J. Am. Chem. Soc.,
2003,
125, 13642-13643.
Terminal alkynes can be directly cross-coupled with alkylzinc reagents in the
presence of a Pd catalyst at room temperature with air as the oxidant. CO was
found to be critical in gaining high chemical yields and selectivities. Good
yields were obtained for a wide range of alkynes and alkylzinc reagents.
M. Chen, X. Zheng, W. Li, J. He, A. Lei, J. Am. Chem. Soc., 2010,
132, 4101-4103.
Hydroboration with catecholborane, followed by treatment with easily
available reagents such as alkenyl sulfones or alkynyl phenyl sulfones in
the presence of a radical initiator, represents an effective and simple
one-pot procedure for direct vinylation, formylation, and cyanation.
A.-P. Schaffner, V. Darmency, P. Renaud, Angew. Chem. Int. Ed.,
2006,
45, 5847-5849.
An efficient protocol for the palladium-catalyzed Heck alkynylation using XPhos
as ligand and Cs2CO3 as the base, couples a wide range of
functionalized terminal alkynes and substituted benzyl chlorides. An excess
amount of base and higher reaction temperatures allows the synthesis of allenes
in a one-pot procedure.
C. H. Larsen, K. W. Anderson, R. E. Tundel, S. L. Buchwald, Synlett, 2006,
2941-2946.
In the presence of Pd(OAc)2 and Xphos, alkynyl carboxylic acids
smoothly underwent a decarboxylative coupling reaction with various benzyl
halides or aryl halides, providing internal alkynes in good yields. It is
noteworthy that the optimal conditions are compatible with a wide range of aryl
halides.
W.-W. Zhang, X.-G. Zhang, J.-H. Li, J. Org. Chem., 2010,
75, 5259-5264.
1,1-diarylpropadienes and
1,3-diarylpropynes can be prepared by the sequential lithiation of
1-aryl-1-propynes, transmetalation, and the corresponding Pd(0)-catalyzed
cross-coupling with aryl halides.
S. Ma, Q. He, X. Zhang, J. Org. Chem., 2005,
70, 3336-3338.
The reaction of alkynylboron dihalides with benzylic, allylic, and
propargylic alcohols provides an efficient route to internal acetylenes
without isomerization of the product alkynes under the reaction conditions.
G. W. Kabalka, M.-L. Yao, S. Borella, Org. Lett.,
2006,
8, 879-881.
Under different conditions, the reaction of propargyl alcohols and terminal
alkynes leads to the selective formation of 1,4-diynes and polysubstituted
furans/pyrroles. Water is the only byproduct in the atom economic, selective
synthesis of 1,4-diynes and pyrroles, whereas the synthesis of furans is fully
atom economic.
T. Wang, X.-l. Chen, L. Chen, Z.-p. Zhan, Org. Lett., 2011,
13, 3324-3327.
A highly diastereoselective addition of terminal alkynes to unsymmetrical
gem-disubstituted cyclopropenes to give alkynylcyclopropanes in good to
excellent yields is catalyzed by the Herrmann-Beller phosphapalladacycle. The
stereofacial discrimination at the approach of the bulky alkynylpalladium
species is believed to be responsible for the diastereoselectivity control of
the addition reaction.
A. Tenaglia, K. Le Jeune, L. Giordano, G. Buono, Org. Lett., 2011,
13, 636-639.
Alkynyl halides serve as a source of Br+ and acetylide ions in an
efficient one-step preparation of alkynyl epoxides, important organic building
blocks, from readily available starting materials.
A. Trofimov, N. Chernyak, V. Gevorgyan, J. Am. Chem. Soc., 2008,
130, 13538-13539.
A rapid and simple conjugate alkynylation of acyclic enones using sp-hybridised
potassium organotrifluoroborates in the presence of BF3•OEt2
is suitable for the preparation of small compound libraries.
F. Bertolini, S. Woodward, Synlett, 2009,
51-54.
An asymmetric 1,3-rearrangement of an alkynyl group of alkynyl alkenyl carbinols
took place in the presence of a hydroxyrhodium/(R)-binap catalyst to
yield β-alkynylketones in high yields with high enantioselectivity. The present
method includes a key β-alkynyl elimination step in the catalytic cycle.
T. Nishimura, T. Katoh, K. Takatshu, R. Shintani, T. Hayashi, J. Am. Chem. Soc., 2007,
129, 14158-14159.
A general, inexpensive, copper-catalyzed coupling of terminal alkynes with
diazo compounds provides ready access to 3-alkynoates. This reaction proceeds efficiently
under nonbasic conditions at room temperature and tolerates various functional
groups.
A. Suárez, G. C. Fu, Angew. Chem. Int. Ed., 2004, 43,
3580-3582.
A carbenoid Fritsch-Buttenberg-Wiechell (FBW) rearrangement of a substituted
dibromoolefinic precursor is used to generate a lithium acetylide, and
subsequent trapping with carbon-based electrophiles provides a wide range of di-
and triynes. The lithium acetylide formed from the FBW reaction can also undergo
transmetalation to provide zinc, copper, tin, or platinum acetylides.
T. Luu, Y. Morisaki, N. Cunningham, R. R. Tykwinski, J. Org. Chem., 2007,
72, 9622-9629.
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