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.
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.
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.
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.
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