Organic Chemistry Portal
Reactions > Organic Synthesis Search

Categories: C-H Bond Formation >

Semireduction of Alkynes

Related: Synthesis of Alkenes


Recent Literature


The reaction of PdCl2 with K2CO3 and HCO2H in dioxane provides a black precipitate, which is an effective catalyst for the semireduction of alkynes to alkenes in the presence of formic acid as the reductant.
R. Iwasaki, E. Tanaka, T. Ichihashi, Y. Idemoto, K. Endo, J. Org. Chem., 2018, 83, 13574-13579.


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 B2Pin2-assisted copper-catalyzed semihydrogenation of alkynes provides various alkenes in good to excellent yields with Z-selectivity under mild reaction conditions. The present protocol enabled convenient synthesis of deuterium-substituted Z-alkenes using readily available ethanol-d1 as the deuterium source.
H. Bao, B. Zhou, H. Jin, Y. Liu, J. Org. Chem., 2019, 84, 3579-3589.


The use of unsupported nanoporous gold (AuNPore) as a heterogeneous catalyst enables a facile, highly chemo- and stereoselective transfer semihydrogenation of alkynes to Z-olefins in the presence of formic acid as a hydrogen donor. Various alkynes were reduced to the corresponding alkenes in high chemical yields with good functional-group tolerance. The catalyst is robust enough to be reused without leaching.
Y. S. Wagh, N. Asao, J. Org. Chem., 2015, 80, 847-851.


A bisacylphosphine oxide photoinitiator was used for a very convenient light mediated preparation of palladium nanoparticles (PdNPs) with a small diameter of 2.8 nm. The PdNP-hybrid material was applied as catalyst for the semihydrogenation of various internal alkynes to provide the corresponding alkenes in excellent yields and Z-selectivities.
F. Mäsing, H. Nüsse, J. Klingauf, A. Studer, Org. Lett., 2017, 19, 2658-2661.


(Tetraphenylporphyrin)palladium can be used as a catalyst for the chemoselective and stereoselective hydrogenation of alkynes to cis-alkenes in good to excellent yields via syn-addition of hydrogen. Alkynes containing various functional groups were tolerated.
R. Nishibayashi, T. Kurahashi, S. Matsubara, Synlett, 2014, 25, 1287-1290.


Copper-catalyzed semihydrogenation of internal alkynes proceeds under an atmosphere of hydrogen (5 atm) at 100 °C in the presence of a readily available catalyst to give various Z-alkenes stereoselectively.
K. Semba, R. Kameyama, Y. Nakao, Synlett, 2015, 26, 318-322.


A cobalt-catalyzed stereodivergent transfer hydrogenation of alkynes provides either Z- or E-alkenes based on a rational catalyst design. Substrates bearing a wide range of functional groups can be hydrogenated in good yields using catalyst loadings as low as 0.2 mol %.
S. Fu, N.-Y. Chen, X. Liu, Z. Shao, S.-P. Luo, Q. Liu, J. Am. Chem. Soc., 2016, 138, 8588-8594.


A cobalt-catalyzed stereodivergent transfer hydrogenation of alkynes provides either Z- or E-alkenes based on a rational catalyst design. Substrates bearing a wide range of functional groups can be hydrogenated in good yields using catalyst loadings as low as 0.2 mol %.
S. Fu, N.-Y. Chen, X. Liu, Z. Shao, S.-P. Luo, Q. Liu, J. Am. Chem. Soc., 2016, 138, 8588-8594.


Ni catalysis enables a transfer hydrogenative alkyne semireduction protocol that can be applied to both internal and terminal alkynes in the presence of formic acid and Zn as the terminal reductants. Both (E)- and (Z)-isomers can be accessed selectively under similar reaction conditions.
E. Richmond, J. Moran, J. Org. Chem., 2015, 80, 6922-6929.


Ni catalysis enables a transfer hydrogenative alkyne semireduction protocol that can be applied to both internal and terminal alkynes in the presence of formic acid and Zn as the terminal reductants. Both (E)- and (Z)-isomers can be accessed selectively under similar reaction conditions.
E. Richmond, J. Moran, J. Org. Chem., 2015, 80, 6922-6929.


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.


Using small amounts of a copper catalyst, an efficient semireduction of alkynes can be accomplished with a wide range of substrates, including both internal and terminal alkynes without over-reduction. The new method has excellent chemoselectivity and tolerates nitro and aryl iodo groups. Finally, commercial availability of a catalyst precursor adds to the appeal of the new catalytic system.
A. M Whittaker, G. Lalic, Org. Lett., 2013, 15, 1112-1115.


Using small amounts of a copper catalyst, an efficient semireduction of alkynes can be accomplished with a wide range of substrates, including both internal and terminal alkynes without over-reduction. The new method has excellent chemoselectivity and tolerates nitro and aryl iodo groups. Finally, commercial availability of a catalyst precursor adds to the appeal of the new catalytic system.
A. M Whittaker, G. Lalic, Org. Lett., 2013, 15, 1112-1115.


Commercial first and second generation Hoveyda-Grubbs catalysts enable a selective transfer semihydrogenation of alkynes to yield alkenes in the presence of formic acid as a hydrogen donor. This catalytic system tolerates many functional groups (halogens, cyano, nitro, sulfide, alkenes).
R. Kusy, K. Grela, Org. Lett., 2016, 18, 6196-6199.


(Ph3P)3RuCl2 is an inexpensive catalyst, that enables a chemoselective reduction of alkyne, ketones, or nitro groups in the presence of Zn/water as a stoichiometric reductant. Depending on the nature of the additive and the temperature, chemoselective reduction of a nitro group in the presence of a ketone or an alkyne was possible.
T. Schabel, C. Belger, B. Plietker, Org. Lett., 2013, 15, 2858-2861.


The use of commercially available reagents (Cl2Pd(PPh3)2, Zn0, and ZnI2) enables an efficient E-selective semihydrogenation of internal alkynes under low dihydrogen pressure and low reaction temperature. The transformation involves syn-hydrogenation followed by isomerization.
R. Maazaoui, R. Abderrahim, F. Chemla, F. Ferreira, A. Perez-Luna, O. Jackowski, Org. Lett., 2018, 20, 7544-7549.


H2Se (or HSe-) produced in situ from Se/DMF/H2O is an active reducing species. This reduction system with water as an inexpensive, safe, and environmentally friendly hydrogen donor displayed high selectivity and good activity in the reduction of α,β-unsaturated ketones and alkynes.
C. An, G. Wu, G.-X. Li, X.-B. Huang, W.X. Gao, J.-C. Ding, Y.-B. Zhou, M.-C. Liu, H.-Y. Wu, Org. Lett., 2018, 20, 5573-5577.


Green water can be used as hydrogen donor for a highly stereoselective and efficient transition-metal-free semihydrogenation of various internal diarylalkynes to E-alkenes. The reactions are conducted under convenient conditions and provide products in good to excellent yields, with broad substrate scope.
Z. Chen, M. Luo, Y. Wen, G. Luo, L. Liu, Org. Lett., 2014, 16, 3020-3023.


DMF/KOH is an efficient hydrogen source in the Pd(OAc)2-catalyzed transfer semihydrogenation of various functionalized internal alkynes to afford cis-alkenes in good to high yields with excellent chemo- and stereoselectivity. This catalytic process was also applied to the synthesis of analogues of combretastatin A-4.
J. Li, R. Hua, T. Liu, J. Org. Chem., 2010, 75, 2966-2970.


γ-Hydroxy-α,β-acetylenic esters are used as precursors for the preparation of γ-hydroxy-α,β-alkenoic esters by means of trans-selective additions of two hydrogen atoms or one hydrogen atom and one iodine atom across the triple bonds. These methods allow the preparation of β-substituted and α,β-disubstituted alkenoic esters in highly stereoselective manners.
C. T. Meta, K. Koide, Org. Lett., 2004, 6, 1785-1787.


The hydrosilylation of alkynes using the ruthenium catalyst [Cp*Ru(MeCN)3]PF6 gives only (Z)-trans addition products. Subsequent protodesilylation of the crude vinylsilane products by the action of cuprous iodide and TBAF provides a general trans-alkyne reduction, which is compatible with many sensitive functional groups.
B. M. Trost, Z. T. Ball, T. Joege, J. Am. Chem. Soc., 2002, 124, 7922-7923.


Indium hydride generated from readily available Et3SiH and InCl3 offers mild conditions and low toxicity, and is therefore a promising alternative to Bu3SnH.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.


A number of alkynyl pinacolboronates were stereoselectively reduced to the cis-alkenyl pinacolboronates via hydroboration with dicyclohexylborane followed by chemoselective protodeboronation using acetic acid. Treatment with potassium hydrogen fluoride smoothly converted these to the corresponding potassium organotrifluoroborates.
G. A. Molander, N. M. Ellis, J. Org. Chem., 2008, 73, 6841-6844.


Indium hydride (Cl2InH) was generated by the transmetalation of InCl3 with Et3SiH. In the previously reported system (NaBH4-InCl3), the coexistent borane can cause side reactions. The use of Et3SiH instead of NaBH4 affords effective hydroindation of alkynes.
N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.