394-46-7Relevant academic research and scientific papers
Base-Mediated Site-Selective Hydroamination of Alkenes
Koh, Ming Joo,Lee, Boon Chong,Li, Ping,Zhang, Xiaoxiang
supporting information, (2021/12/29)
We present a base-mediated hydroamination protocol, using substoichiometric amounts of a hydrosilane and potassium tertbutoxide, that operates under mild conditions at 30 °C. Many aryl- and heteroatom-substituted olefins as well as arylamines are tolerated, affording the desired products with complete regioselectivity. Preliminary mechanistic investigations reveal a non-radical pathway for hydroamination. A sequential remote hydroamination strategy involving an initial Fe-catalysed olefin isomerisation followed by our base-mediated hydroamination was also developed to directly access-arylamines from terminal aliphatic alkenes.
An Annelated Mesoionic Carbene (MIC) Based Ru(II) Catalyst for Chemo- And Stereoselective Semihydrogenation of Internal and Terminal Alkynes
Bera, Jitendra K.,Choudhury, Joyanta,Das, Shubhajit,Dutta, Indranil,Pati, Swapan K.,Saha, Sayantani,Yadav, Suman
, p. 3212 - 3223 (2020/10/02)
The catalytic utility of [RuL1(CO)2I2] (1), containing an annelated π-conjugated imidazo-naphthyridine-based mesoionic carbene (MIC) ligand (L1), is evaluated for E-selective alkyne semihydrogenation. The precatalyst 1, in combination with 2 equiv of AgBArF, semihydrogenates a broad range of internal alkynes with molecular hydrogen (5 bar) in water. (E)-Alkenes are accessed in high yields, and a number of reducible functional groups are tolerated. A chelate MIC ligand and two cis carbonyls provide a well-defined platform at the Ru center for hydrogenation and isomerization. The loss of two iodides and the presence of two carbonyls render the Ru center electron deficient and thus the formation of metal vinylidenes with terminal alkynes is avoided. This is leveraged for the semihydrogenation of terminal alkynes by the same catalytic system in isopropyl alcohol. Reaction profile, isomerization, kinetic, and DFT studies reveal initial alkyne hydrogenation to a (Z)-alkene, which further isomerizes to an (E)-alkene via metal-catalyzed Z → E isomerization.
Accelerating Chemo- And Regioselective Hydrogenation of Alkynes over Bimetallic Nanoparticles in a Metal-Organic Framework
Guan, Qiaoqiao,Jiang, Hai-Long,Li, Luyan,Lu, Junling,Yang, Qihao,Yang, Weijie,Yu, Shu-Hong
, p. 7753 - 7762 (2020/08/21)
Selective semihydrogenation of alkynes has been a long-term and significant target, yet it remains a great challenge. Herein, bimetallic nanoparticles in a metal-organic framework (MOF), i.e., CuPd&at;ZIF-8 composite, featuring a cubic CuPd core and a porous ZIF-8 shell, have been rationally fabricated for this end. Given the unique physicochemical properties, the Cu nanocubes can not only convert solar energy into heat to accelerate the reaction but also serve as the seed for in situ formation of Pd nanoparticles (NPs) on their external surface to regulate the chemoselectivity of Pd active sites. The additional growth of the MOF shell is helpful to stabilize the CuPd core and offer regioselectivity via the steric hindrance effect. Ammonia borane provides active hydrogen species to significantly boost the hydrogenation and ensure the high selectivity. As a result, the CuPd&at;MOF exhibits high efficiency, featuring a turnover frequency (TOF, 6799 min-1) of 5-105 times higher than that in previous reports, and high chemo- and regioselectivity toward the semihydrogenation of alkynes, in the presence of NH3BH3 as a hydrogen source, under visible-light irradiation at ambient temperature.
Synthesis of Unprotected 2-Arylglycines by Transamination of Arylglyoxylic Acids with 2-(2-Chlorophenyl)glycine
Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
, p. 11047 - 11059 (2020/10/12)
The transamination of α-keto acids with 2-phenylglycine is an effective methodology for directly synthesizing unprotected α-amino acids. However, the synthesis of 2-arylglycines by transamination is problematic because the corresponding products, 2-arylglycines, transaminate the starting arylglyoxylic acids. Herein, we demonstrate the use of commercially available l-2-(2-chlorophenyl)glycine as the nitrogen source in the transamination of arylglyoxylic acids, producing the corresponding 2-arylglycines without interference from the undesired self-transamination process.
Monodisperse nickel-nanoparticles for stereo- and chemoselective hydrogenation of alkynes to alkenes
Murugesan, Kathiravan,Alshammari, Ahmad S.,Sohail, Manzar,Beller, Matthias,Jagadeesh, Rajenahally V.
, p. 372 - 377 (2019/01/26)
Here, we report the use of monosaccharides for the preparation of novel nickel nanoparticles (NP), which constitute selective hydrogenation catalysts. For example, immobilization of fructose and Ni(OAc)2 on silica and subsequent pyrolysis under inert atmosphere produced graphitic shells encapsulated Ni-NP with uniform size and distribution. Interestingly, fructose acts as structure controlling compound to generate specific graphitic layers and the formation of monodisperse NP. The resulting stable and reusable catalysts allow for stereo- and chemoselective semihydrogenation of functionalized and structurally diverse alkynes in high yields and selectivity.
Towards nitrile-substituted cyclopropanes-a slow-release protocol for safe and scalable applications of diazo acetonitrile
Hock, Katharina J.,Spitzner, Robin,Koenigs, Rene M.
supporting information, p. 2118 - 2122 (2017/07/24)
Diazo acetonitrile has long been neglected despite its high value in organic synthesis due to a high risk of explosions. Herein, we report our efforts towards the transient and safe generation of this diazo compound, its applications in iron catalyzed cyclopropanation and cyclopropenation reactions and the gram-scale synthesis of cyclopropyl nitriles.
Photoinduced, copper-catalyzed three components cyanofluoroalkylation of alkenes with fluoroalkyl iodides as fluoroalkylation reagents
Guo, Quanping,Wang, Mengran,Wang, Yanfang,Xu, Zhaoqing,Wang, Rui
supporting information, p. 12317 - 12320 (2017/11/20)
In the past few years, Ru and Ir catalyzed photoredox radical coupling reactions have been widely applied in organic synthesis. In contrast, the applications of Cu catalysts in photoredox organic transformations were limited. We here report the first example of photoinduced, Cu-catalyzed three component cyanofluoroalkylation of alkenes by directly using fluoroalkyl iodides as fluoroalkylation reagents.
Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions
Haubenreisser, Stefan,W?ste, Thorsten H.,Martnez, Claudio,Ishihara, Kazuaki,Muiz, Kilian
supporting information, p. 413 - 417 (2016/01/25)
Molecular structures of the most prominent chiral non-racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen-bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.
Remazol-Catalyzed Hydroperoxyarylation of Styrenes
Chen, Ying-Ho,Lee, Ming,Lin, Yi-Zhen,Leow, Dasheng
supporting information, p. 1618 - 1621 (2015/08/06)
A mild photocatalytic hydroperoxyarylation of styrenes has been developed, in which a novel photocatalyst, remazol brilliant blue R (RBBR), is employed at low catalytic loading (1 mol%). The operationally easy procedure uses air as the dioxygen source. Simple mono-substituted styrenes react with aryl hydrazines in moderate-to-good yields. RBBR is proposed to act as a photosensitizer for the generation of singlet oxygen.
Heck, Sonogashira, and Hiyama reactions catalyzed by palladium nanoparticles stabilized by tris-imidazolium salt
Planellas, Marc,Moglie, Yanina,Alonso, Francisco,Yus, Miguel,Pleixats, Roser,Shafir, Alexandr
supporting information, p. 3001 - 3008 (2014/05/20)
Palladium nanoparticles, prepared by the hydrogenation of Pd(dba) 2 in the presence of a tris-imidazolium iodide as stabilizer, act as an efficient catalyst for Heck and copper-free Sonogashira reactions with a range of aryl iodides and bromides at 0.2 mol-% Pd loading. Moreover, we describe a convenient protocol for the fluoride-free Hiyama coupling of vinylsilanes with aryl iodides that involves the use of sodium hydroxide as promoter in a methanol/water mixture. Under the developed conditions, one-pot, double Heck and Hiyama-Heck reactions are successfully achieved.
