5669-43-2Relevant academic research and scientific papers
One-Pot Synthesis of Primary and Secondary Aliphatic Amines via Mild and Selective sp3 C?H Imination
Comito, Robert J.,Ghosh, Subrata K.,Hu, Mengnan
supporting information, p. 17601 - 17608 (2021/11/03)
The direct replacement of sp3 C?H bonds with simple amine units (?NH2) remains synthetically challenging, although primary aliphatic amines are ubiquitous in medicinal chemistry and natural product synthesis. We report a mild and selective protocol for preparing primary and secondary aliphatic amines in a single pot, based on intermolecular sp3 C?H imination. The first C?H imination of diverse alkanes, this method shows useful site-selectivity within substrates bearing multiple sp3 C?H bonds. Furthermore, this reaction tolerates polar functional groups relevant for complex molecule synthesis, highlighted in the synthesis of amine pharmaceuticals and amination of natural products. We characterize a unique C?H imination mechanism based on radical rebound to an iminyl radical, supported by kinetic isotope effects, stereoablation, resubmission, and computational modeling. This work constitutes a selective method for complex amine synthesis and a new mechanistic platform for C?H amination.
Hydrosilylation and Mukaiyama aldol-type reaction of quinolines and hydrosilylation of imines catalyzed by a mesoionic carbene-stabilized borenium ion
Bestvater, Brian P.,Clarke, Joshua J.,Crudden, Cathleen M.,DeJesus, Joseph F.,Devaraj, Karthik,Eisenberger, Patrick,Kojima, Ryoto
supporting information, p. 6786 - 6791 (2021/08/20)
Aldimines and ketimines containing electron-donating and electron-withdrawing groups can be hydrosilylated with borenium catalysts at as low as 1 mol% catalyst loading at room temperature, providing the corresponding secondary amines in excellent yields. Reactions with 2-phenylquinoline gave the 1,4-hydrosilylquinoline product selectively which can be further functionalized in a one-pot synthesis to give unique γ-amino alcohol derivatives. Control experiments suggest that the borenium ion catalyzes both the hydrosilylation and subsequent addition to the aldehyde.
Two isostructural URJC-4 materials: From hydrogen physisorption to heterogeneous reductive amination through hydrogen molecule activation at low pressure
Montes-Andrés, Helena,Leo, Pedro,Mu?oz, Antonio,Rodríguez-Diéguez, Antonio,Orcajo, Gisela,Choquesillo-Lazarte, Duane,Martos, Carmen,Martínez, Fernando,Botas, Juan A.,Calleja, Guillermo
supporting information, p. 15733 - 15740 (2020/11/02)
Herein, two novel isostructural metal-organic frameworks (MOFs) M-URJC-4 (M = Co, Ni; URJC = "Universidad Rey Juan Carlos") with open metal sites, permanent microposity, and large surface areas and pore volumes have been developed. These novel MOFs, with polyhedral morphology, crystallize in the monoclinic P21/c space group, exhibiting a three-dimensional structure with microporous channels along the c axis. Initially, they were fully characterized and tested in hydrogen (H2) adsorption at different conditions of temperature and pressure. The physisorption capacities of both materials surpassed the gravimetric H2 uptake shown by most MOF materials under the same conditions. On the basis of the outstanding adsorption properties, the Ni-URJC-4 material was used as a catalyst in a one-pot reductive amination reaction using various carbonyl compounds and primary amines. A possible chemical pathway to obtain secondary amines was proposed via imine formation, and remarkable performances were accomplished. This work evidences the dual ability of M-URJC-4 materials to be used as a H2 adsorbent and a catalyst in reductive amination reactions, activating molecular H2 at low pressures for the reduction of C=N double bonds and providing reference structural features for the design of new versatile heterogeneous materials for industrial application.
Stable group 8 metal porphyrin mono- And bis(dialkylcarbene) complexes: Synthesis, characterization, and catalytic activity
Che, Chi-Ming,Huang, Jie-Sheng,Low, Kam-Hung,Wan, Qingyun,Wang, Hai-Xu,Zhang, Jun-Long,Zhou, Cong-Ying
, p. 2243 - 2259 (2020/03/11)
Alkyl-substituted carbene (CHR or CR2, R = alkyl) complexes have been extensively studied for alkylcarbene (CHR) ligands coordinated with high-valent early transition metal ions (a.k.a. Schrock carbenes or alkylidenes), yet dialkylcarbene (CR2) complexes remain less developed with bis(dialkylcarbene) species being little (if at all) explored. Herein, several group 8 metal porphyrin dialkylcarbene complexes, including Fe- and Ru-mono(dialkylcarbene) complexes [M(Por)(Ad)] (1a,b, M = Fe, Por = porphyrinato dianion, Ad = 2-adamantylidene; 2a,b, M = Ru) and Os-bis(dialkylcarbene) complexes [Os(Por)(Ad)2] (3a-c), are synthesized and crystallographically characterized. Detailed investigations into their electronic structures reveal that these complexes are formally low-valent M(ii)-carbene in nature. These complexes display remarkable thermal stability and chemical inertness, which are rationalized by a synergistic effect of strong metal-carbene covalency, hyperconjugation, and a rigid diamondoid carbene skeleton. Various spectroscopic techniques and DFT calculations suggest that the dialkylcarbene Ad ligand is unique compared to other common carbene ligands as it acts as both a potent σ-donor and π-acceptor; its unique electronic and structural features, together with the steric effect of the porphyrin macrocycle, make its Fe porphyrin complex 1a an active and robust catalyst for intermolecular diarylcarbene transfer reactions including cyclopropanation (up to 90% yield) and X-H (X = S, N, O, C) insertion (up to 99% yield) reactions.
Selective Synthesis of Secondary Amines from Nitriles by a User-Friendly Cobalt Catalyst
Sharma, Dipesh M.,Punji, Benudhar
supporting information, p. 3930 - 3936 (2019/07/12)
Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3?BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH?BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities. (Figure presented.).
Cu-Catalyzed Desulfonylative Amination of Benzhydryl Sulfones
Nambo, Masakazu,Tahara, Yasuyo,Yim, Jacky C.-H.,Crudden, Cathleen M.
supporting information, p. 1923 - 1926 (2019/01/24)
A new method for the synthesis of benzhydryl amines from the reaction of readily available sulfone derivatives with amines is described. The Cu-catalyzed desulfonylative amination not only provides structurally diverse benzhydryl amines in good yields, but is also applicable to iterative and intramolecular aminations. Control experiments suggested that the formation of a Cu-carbene intermediate generated from the sulfone substrate, which represents a new route for desulfonylative transformations.
Improving C=N bond reductions with (Cyclopentadienone)iron complexes: Scope and limitations
Cettolin, Mattia,Bai, Xishan,Lübken, Dennis,Gatti, Marco,Facchini, Sofia Vailati,Piarulli, Umberto,Pignataro, Luca,Gennari, Cesare
, p. 647 - 654 (2018/10/24)
Herein, we broaden the application scope of (cyclo-pentadienone)iron complexes 1 in C=N bond reduction. The catalytic scope of pre-catalyst 1b, which is more active than the “Kn?lker complex” (1a) and other members of its family, has been expanded to the catalytic transfer hydrogenation (CTH) of a wider range of aldimines and ketimines, either pre-isolated or generated in situ. The kinetics of 1b-promoted CTH of ketimine S1 were assessed, showing a pseudo-first order profile, with TOF = 6.07 h–1 at 50 % conversion. Moreover, the chiral complex 1c and its analog 1d were employed in the enantioselective reduction of ketimines and reductive amination of ketones, giving fair to good yields and moderate enantioselectivity.
Promoting Frustrated Lewis Pairs for Heterogeneous Chemoselective Hydrogenation via the Tailored Pore Environment within Metal–Organic Frameworks
Niu, Zheng,Zhang, Weijie,Lan, Pui Ching,Aguila, Briana,Ma, Shengqian
supporting information, p. 7420 - 7424 (2019/04/27)
Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal-free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β-unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β-unsaturated imine substrates to afford unsaturated amine compounds.
Photocatalytic and Chemoselective Transfer Hydrogenation of Diarylimines in Batch and Continuous Flow
Van As, Dean J.,Connell, Timothy U.,Brzozowski, Martin,Scully, Andrew D.,Polyzos, Anastasios
, p. 905 - 908 (2018/02/22)
A visible-light photocalytic method for the chemoselective transfer hydrogenation of imines in batch and continuous flow is described. The reaction utilizes Et3N as both hydrogen source and single-electron donor, enabling the selective reduction of imines derived from diarylketimines containing other reducible functional groups including nitriles, halides, esters, and ketones. The dual role of Et3N was confirmed by fluorescence quenching measurements, transient absorption spectroscopy, and deuterium-labeling studies. Continuous-flow processing facilitates straightforward scale-up of the reaction.
Correction to: Photocatalytic and Chemoselective Transfer Hydrogenation of Diarylimines in Batch and Continuous Flow (Organic Letters (2018) 20:4 (905-908) DOI: 10.1021/acs.orglett.7b03565)
Van As, Dean J.,Connell, Timothy U.,Brzozowski, Martin,Scully, Andrew D.,Polyzos, Anastasios
, p. 4392 - 4392 (2018/07/29)
Sections of Schemes 2 and 4 were omitted in error during the production process. The complete versions of Schemes 2 and 4 are shown below.(Figure Persented).Scheme 2 is corrected as follows:.
