Categories: C-H Bond Formation >
Reduction of Alkynes
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An unprecedented reduction of alkynes with formic acid can selectively
produce cis-, trans-alkenes and alkanes by slightly tuning the
reaction conditions via the generation of an alkenylpalladium intermediate and
subsequent transformation of this complex in a variety of reactions catalyzed by
a combination of Brønsted acid and Pd(0) complex.
R. Shen, T. Chen, Y. Zhao, R. Qiu, Y. Zhou, S. Yin, X. Wang, M. Goto, L.-B. Han, J. Am. Chem. Soc., 2011,
133, 17037-17044.
A Pd/C-catalyzed hydrogenation using diphenylsulfide as a catalyst poison
selectively reduces olefin and acetylene functionalities without
hydrogenolysis of aromatic carbonyls and halogens, benzyl esters, and N-Cbz
protective groups.
A. Mori, Y. Miyakawa, E. Ohashi, T. Haga, T. Maegawa, H. Sajiki, Org.
Lett.,
2006,
8, 3279-3281.
A new recyclable catalyst composed of palladium nanoparticles dispersed in
an organic polymer was synthesized by a simple procedure from readily
available reagents. This catalyst is robust, and highly active in many
organic transformations including alkene and alkyne hydrogenation,
carbon-carbon cross-coupling reactions, and aerobic alcohol oxidation.
C. M. Park, M. S. Kwon, J. Park,
Synthesis, 2006, 3790-3794.
A NCP-type pincer iridium complex enables an efficient, mild, chemoselective
transfer hydrogenation of unactivated C-C multiple bonds with ethanol, forming
ethyl acetate as the sole byproduct. A wide variety of alkenes, including
multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted
alkenes, as well as heteroarenes and internal alkynes, are suitable substrates.
Y. Wang, Z. Huang, X. Leng, H. Zhu, G. Liu, Z. Huang, J. Am. Chem. Soc.,
2018,
140, 4417-4429.
In situ generation of molecular hydrogen by addition of triethylsilane to
palladium on charcoal results in rapid and efficient reduction of multiple bonds,
azides, imines, and nitro groups, as well as deprotection of benzyl and allyl
groups under mild, neutral conditions.
P. K. Mandal, J. S. McMurray, J. Org. Chem.,
2007,
72, 6599-6601.
A generally applicable method for the introduction of gaseous hydrogen into a
sealed reaction system under microwave irradiation allows the hydrogenation of
various substrates in short reaction times with moderate temperatures between 80
°C and 100 °C with 50 psi of hydrogen.
G. S. Vanier, Synlett, 2007, 131-135.
The use of hydrogen micro and nanobubbles (MNBs) enables an autoclave-free,
gas-liquid-solid multiphase hydrogenation of carbon-carbon unsaturated bonds, in
which a high concentration of hydrogen gas is maintained in the liquid phase.
N. Mase, S. Isomura, M. Toda, N. Watanabe, Synlett, 2013, 24,
2225-2228.
In situ preparation of an active Pd/C catalyst from Pd(OAc)2 and
charcoal in methanol enables a simple, highly reproducible protocol for the
hydrogenation of alkenes and alkynes and for the hydrogenolysis of O-benzyl
ethers. Mild reaction conditions and low catalyst loadings, as well as the
absence of contamination of the product by palladium residues, make this a
sustainable, useful process.
F.-X. Felpin, E. Fouquet, Chem. Eur. J., 2010, 12440-12445.