Buchwald–Hartwig Amination of Nitroarenes Inoue, Fumiyoshi; Kashihara, Myuto; Yadav, M. Ramu ...
Angewandte Chemie International Edition,
October 16, 2017, Letnik:
56, Številka:
43
Journal Article
Recenzirano
The Buchwald–Hartwig amination of nitroarenes was achieved for the first time by using palladium catalysts bearing dialkyl(biaryl)phosphine ligands. These cross‐coupling reactions of nitroarenes with ...diarylamines, arylamines, and alkylamines afforded the corresponding substituted arylamines. A catalytic cycle involving the oxidative addition of the Ar−NO2 bond to palladium(0) followed by nitrite/amine exchange is proposed based on a stoichiometric reaction.
Nitro to amino: The Buchwald–Hartwig amination of nitroarenes is catalyzed by a palladium complex bearing a dialkyl(biaryl)phosphine ligand. Nitroarenes were thus cross‐coupled with diarylamines, arylamines, and alkylamines to afford the corresponding substituted arylamines.
Herein, we have demonstrated an operationally simple Pd-catalyzed double-Heck reaction between N-(o-bromoaryl)acrylamide derivatives and α-fluoro/trifluoromethyl acrylates to enable ...monofluoro/trifluoromethyl alkene tethered 3,3-disubstituted oxindoles in a stereoselective manner. Remarkably, the reaction proceeds well without any external ligand in an open-air atmosphere. Control experiments and spectroscopic analysis are performed to understand the reaction mechanism.
Reductive Denitration of Nitroarenes Kashihara, Myuto; Yadav, M. Ramu; Nakao, Yoshiaki
Organic letters,
03/2018, Letnik:
20, Številka:
6
Journal Article
Recenzirano
The Pd-catalyzed reductive denitration of nitroarenes has been achieved via a direct cleavage of the C–NO2 bonds. The catalytic conditions reported exhibit a broad substrate scope and good ...functional-group compatibility. Notably, the use of inexpensive propan-2-ol as a mild reductant suppresses the competitive formation of anilines, which are normally formed by other conventional reductions. Mechanistic studies have revealed that alcohols serve as efficient hydride donors in this reaction, possibly through β-hydride elimination from palladium alkoxides.
Decarboxylative coupling reactions using readily available (hetero)aryl carboxylic acids are a highly efficient approach for the formation of new C-C and C-X bonds. These decarboxylative coupling ...reactions eliminate CO
2
as a by-product, resulting in a greener and environmentally more benign approach than conventional coupling reactions. In this review, we summarize the recent developments in
ipso
-decarboxylative C-X (X = O/N/halo/S/Se/P/CN) bond formations using (hetero)aryl carboxylic acids. Furthermore, we highlight the current limitations and future research opportunities of aryl-decarboxylative coupling reactions.
This review highlights the recent developments in
ipso
-decarboxylative C-X (X = O/N/halo/S/Se/P/CN) bond formation using (hetero)aryl carboxylic acids, which are economical and environmentally benign starting materials.
With the aid of a novel S-methyl-S-2-pyridyl-sulfoximine (MPyS) directing group (DG), the unactivated primary β-C(sp3)–H bond of MPyS-N-amides oxidizes at room temperature. The catalytic conditions ...are applicable to the diacetoxylation of primary β,β′-C(sp3)–H bonds, and the carboxylic acid solvent is pivotal in the formation of the C–O bond. The MPyS-DG cleaves from the oxidation products and is recovered. This method provides convenient access to α,α′-disubstituted-β-hydroxycarboxylic acids.
The Suzuki–Miyaura Coupling of Nitroarenes Yadav, M. Ramu; Nagaoka, Masahiro; Kashihara, Myuto ...
Journal of the American Chemical Society,
07/2017, Letnik:
139, Številka:
28
Journal Article
Recenzirano
Synthesis of biaryls via the Suzuki–Miyaura coupling (SMC) reaction using nitroarenes as an electrophilic coupling partners is described. Mechanistic studies have revealed that the catalytic cycle of ...this reaction is initiated by the cleavage of the aryl–nitro (Ar–NO2) bond by palladium, which represents an unprecedented elemental reaction.
This investigation highlights the performance of high‐performance polymeric composite for ballistic application. Therefore, reinforcement of para‐aramid fiber in poly‐ether‐ketone‐ketone (PEKK) resin ...film has been made. The surface of PEKK and para‐aramid fiber was modified by low‐pressure plasma to enhance the surface energy of the polymeric film and reinforcement fiber. The polymeric composite was manufactured by compression molding with a pressure of 2 bar, temperature of 310°C with holding time of 15 min. Due to low‐pressure plasma treatment of PEKK film and para‐aramid fiber, the tensile strength of the composites increases considerably. In the accelerated aging test, the tensile specimens are dipped into concentrated HNO3 and NaOH medium for 15 days. It is observed that there is a decrease in tensile strength. The ultimate tensile strength (UTS) of the virgin specimen was compared to the environmentally aged for 15 days and in this case, also there was a decrease in tensile strength. Two types of composite panels were made (i) 25 layers of PEKK film with 24 layers of para‐aramid fabric and (ii) 45 layers of PEKK film with 44 layers of para‐aramid fabric with 15 mm × 15 mm. The composite panel was tested with four 9 mm handgun bullets fired from a distance of 5 meters with a speed of 430 m/s. In the case of 25 layers of PEKK film with 24 layers of para‐aramid fabric, the composite failed under ballistic test, however, in the case of 45 layers of PEKK film with 44 layers of para‐aramid fabric, the composite was successful under ballistic test.
Highlights
Film stacking method of PEKK and Aramid fiber.
Ballistic composite panel with layers of PEKK and Aramid fiber.
Enhancement of mechanical properties of the composite panel with plasma surface treatment.
Ballistic testing of composite panel.
High performance polymeric composite for ballistic applications.
Establishing ultimate spin current efficiency in graphene over industry-standard substrates can facilitate research and development exploration of spin current functions and spin sensing. At the same ...time, it can resolve core issues in spin relaxation physics while addressing the skepticism of graphene’s practicality for planar spintronic applications. In this work, we reveal an exceptionally long spin communication capability of 45 μm and highest to date spin diffusion length of 13.6 μm in graphene on SiO2/Si at room temperature. Employing commercial chemical vapor deposited (CVD) graphene, we show how contact-induced surface charge transfer doping and device doping contributions, as well as spin relaxation, can be quenched in extremely long spin channels and thereby enable unexpectedly long spin diffusion lengths in polycrystalline CVD graphene. Extensive experiments show enhanced spin transport and precession in multiple longest channels (36 and 45 μm) that reveal the highest spin lifetime of ∼2.5–3.5 ns in graphene over SiO2/Si, even under ambient conditions. Such performance, made possible due to our devices approaching the intrinsic spin–orbit coupling of ∼20 μeV in graphene, reveals the role of the D’yakonov–Perel’ spin relaxation mechanism in graphene channels as well as contact regions. Our record demonstration, fresh device engineering, and spin relaxation insights unlock the ultimate spin current capabilities of graphene on SiO2/Si, while the robust high performance of commercial CVD graphene can proliferate research and development of innovative spin sensors and spin computing circuits.
The Ru(II)-catalyzed intermolecular o-C–H amidation of arenes in N-benzoylated sulfoximine with sulfonyl azides is demonstrated. The reaction proceeds with broad substrate scope and tolerates various ...functional groups. Base hydrolysis of the amidation product provides the anthranilic acid derivatives and methylphenyl sulfoximine (MPS) directing group. This method is successfully employed for the synthesis of HMR 1766.
Metal- and additive-free, photoinduced decarboxylative radical alkylation–cyclization of CF3-acrylamides with alkyl redox-active esters provided the corresponding quaternary CF3-oxindole derivatives ...in good yields. Notably, diaryliodonium salts also efficiently participated in the arylation–cyclization of CF3-acrylamides in environmentally benign H2O as a solvent. The present approach has been extended for the concise synthesis of CF3-attached indoline alkaloid analogues, i.e., CF3-(±)-desoxyeseroline, CF3-(±)-esermethole, and CF3-(±) progesterone receptor antagonists. The preliminary mechanistic studies revealed that the reaction is likely to proceed through initial photoexcitation of redox-active ester/diaryliodonium salts followed by the SET process with acrylamide.
PDF
