Ligand-free (Z)-selective transfer semihydrogenation of alkynes catalyzed by in situ generated oxidizable copper nanoparticles

Abstract

Herein, we present (Z)-selective transfer semihydrogenation of alkynes based on in situ generated CuNPs in the presence of hydrogen donors, such as ammonia-borane and a green protic solvent. This environmentally-friendly...

Stereoselective Semi‐Hydrogenations of Alkynes by First‐Row (3d) Transition Metal Catalysts

“…At the same time, Kusy and Grela presented a similar approach, using CuCl 2 2H 2 O instead to generate the CuNPs in situ using ammonia‐borane in a water/THF mixture. [120] This approach gave similarly satisfactory results as the system by Park et al. Though with slightly higher temperatures (60 °C) and reaction times of up to 24 h, the authors achieved a lower catalyst loading (2 mol%) with a lower excess of H 3 N‐BH 3 (2 equiv.)…”

“…Usually, yields and Z ‐selectivies >90 % were achieved, albeit with trace amounts of alkane occasionally being detected. At the same time, Kusy and Grela presented a similar approach, using CuCl 2 2H 2 O instead to generate the CuNPs in situ using ammonia‐borane in a water/THF mixture [120] . This approach gave similarly satisfactory results as the system by Park et al.…”

H2O as the Hydrogen Donor: Stereo-Selective Synthesis of E- and Z-Alkenes by Palladium-Catalyzed Semihydrogenation of Alkynes

“…3b : ( Z )-1-Fluoro-4-styrylbenzene, 74 colorless liquid (18.8 mg, 95% yield). 1 H NMR (400 MHz, CDCl 3 ): δ 7.24–7.18 (m, 7H), 6.91 (t, J = 8.0 Hz, 2H), 6.57 (dd, J = 20.0, 12.0 Hz, 2H); 13 C NMR (100 MHz, CDCl 3 ): δ 137.15, 130.65 (d, J C–F = 7.9 Hz), 130.38, 129.20, 128.95, 128.44, 127.32, 115.39, 115.18.…”

Maximizing hydrogen utilization efficiency in tandem hydrogenation of nitroarenes with ammonia borane

“…Thus, combining AB dehydrogenation with organic hydrogenation using heterogeneous catalysts has sparked enormous interest for green chemistry synthesis because the usage of pure H 2 and harsh reaction conditions can be avoided. [18][19][20][21][22][23][24][25][26][27][28][29][30] Generating H 2 in situ during the reaction avoids H 2 transportation, handling, and storage, allowing for reduced capital cost and enhanced safety. In addition, it avoids the gas-liquid mass transfer with associated coefficient k L a [s −1 ] from the head-space of a traditional vessel, 31 as the H 2 is generated at the reactive site of the catalyst exactly where it is needed.…”