156-28-5Relevant articles and documents
Regio- and stereoselective hydroamination of alkynes using an ammonia surrogate: Synthesis of N -Silylenamines as reactive synthons
Lui, Erica K. J.,Brandt, Jason W.,Schafer, Laurel L.
, p. 4973 - 4976 (2018)
An anti-Markovnikov selective hydroamination of alkynes with N-silylamines to afford N-silylenamines is reported. The reaction is catalyzed by a bis(amidate)bis(amido)Ti(IV) catalyst and is compatible with a variety of terminal and internal alkynes. Stoichiometric mechanistic studies were also performed. This method easily affords interesting N-silylenamine synthons in good to excellent yields and the easily removable silyl protecting group enables the catalytic synthesis of primary amines.
Hydroborative reduction of amides to amines mediated by La(CH2C6H4NMe2-: O)3
Gong, Mingliang,Guo, Chenjun,Luo, Yunjie,Xie, Hongzhen,Zhang, Fangcao
, p. 779 - 791 (2022/01/22)
The deoxygenative reduction of amides to amines is a great challenge for resonance-stabilized carboxamide moieties, although this synthetic strategy is an attractive approach to access the corresponding amines. La(CH2C6H4NMe2-o)3, a simple and easily accessible lanthanide complex, was found to be highly efficient not only for secondary and tertiary amide reduction, but also for the most challenging primary reduction with pinacolborane. This protocol exhibited good tolerance for many functional groups and heteroatoms, and could be applied to gram-scale synthesis. The active species in this catalytic cycle was likely a lanthanide hydride.
Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
supporting information, p. 1618 - 1629 (2021/01/25)
Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
Green method for catalyzing reduction reaction of aliphatic nitro derivative
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Paragraph 0005-0006; 0081-0084, (2021/07/31)
The invention relates to a green method for catalyzing reduction reaction of aliphatic nitro derivatives. According to the method, non-transition metal compounds, namely triethyl boron and potassium tert-butoxide, are used as a catalytic system for the first time, an aliphatic nitro derivative and pinacolborane which is low in price and easy to obtain are catalyzed to be subjected to a reduction reaction under mild conditions, and an aliphatic amine hydrochloride product is synthesized after acidification with a hydrochloric acid aqueous solution. Compared with a traditional method, the method generally has the advantages that the catalyst is cheap and easy to obtain, operation is convenient, and reaction is safe. The selective reduction reaction of the aliphatic nitro derivative catalyzed by the non-transition metal catalyst and pinacol borane is realized for the first time, and the aliphatic amine hydrochloride product is synthesized through acidification treatment of the hydrochloric acid aqueous solution, so that a practical new reaction strategy is provided for laboratory preparation or industrial production.
Hydrosilylative reduction of primary amides to primary amines catalyzed by a terminal [Ni-OH] complex
Bera, Jitendra K.,Pandey, Pragati
supporting information, p. 9204 - 9207 (2021/09/20)
A terminal [Ni-OH] complex1, supported by triflamide-functionalized NHC ligands, catalyzes the hydrosilylative reduction of a range of primary amides into primary amines in good to excellent yields under base-free conditions with key functional group tolerance. Catalyst1is also effective for the reduction of a variety of tertiary and secondary amides. In contrast to literature reports, the reactivity of1towards amide reduction follows an inverse trend,i.e., 1° amide > 3° amide > 2° amide. The reaction does not follow a usual dehydration pathway.
Lithium compound catalyzed deoxygenative hydroboration of primary, secondary and tertiary amides
Bisai, Milan Kumar,Gour, Kritika,Das, Tamal,Vanka, Kumar,Sen, Sakya S.
supporting information, p. 2354 - 2358 (2021/03/03)
A selective and efficient route for the deoxygenative reduction of primary to tertiary amides to corresponding amines has been achieved with pinacolborane (HBpin) using simple and readily accessible 2,6-di-tert-butyl phenolate lithium·THF (1a) as a catalyst. Both experimental and DFT studies provide mechanistic insight. This journal is
Reduction of Amides to Amines with Pinacolborane Catalyzed by Heterogeneous Lanthanum Catalyst La(CH2C6H4NMe2- o)3@SBA-15
Guo, Chenjun,Zhang, Fangcao,Yu, Chong,Luo, Yunjie
supporting information, p. 13122 - 13135 (2021/08/31)
Hydroboration of amides is a useful synthetic strategy to access the corresponding amines. In this contribution, it was found that the supported lanthanum benzyl material La(CH2C6H4NMe2-o)3@SBA-15 was highly active for the hydroboration of primary, secondary, and tertiary amides to amines with pinacolborane. These reactions selectively produced target amines and showed good tolerance for functional groups such as -NO2, -halogen, and -CN, as well as heteroatoms such as S and O. This reduction procedure exhibited the recyclable and reusable property of heterogeneous catalysts and was applicable to gram-scale synthesis. The reaction mechanisms were proposed based on some control experiments and the previous literature. This is the first example of hydroborative reduction of amides to amines mediated by heterogeneous catalysts.
Phosphine-Free Manganese Catalyst Enables Selective Transfer Hydrogenation of Nitriles to Primary and Secondary Amines Using Ammonia-Borane
Sarkar, Koushik,Das, Kuhali,Kundu, Abhishek,Adhikari, Debashis,Maji, Biplab
, p. 2786 - 2794 (2021/03/03)
Herein we report the synthesis of primary and secondary amines by nitrile hydrogenation, employing a borrowing hydrogenation strategy. A class of phosphine-free manganese(I) complexes bearing sulfur side arms catalyzed the reaction under mild reaction conditions, where ammonia-borane is used as the source of hydrogen. The synthetic protocol is chemodivergent, as the final product is either primary or secondary amine, which can be controlled by changing the catalyst structure and the polarity of the reaction medium. The significant advantage of this method is that the protocol operates without externally added base or other additives as well as obviates the use of high-pressure dihydrogen gas required for other nitrile hydrogenation reactions. Utilizing this method, a wide variety of primary and symmetric and asymmetric secondary amines were synthesized in high yields. A mechanistic study involving kinetic experiments and high-level DFT computations revealed that both outer-sphere dehydrogenation and inner-sphere hydrogenation were predominantly operative in the catalytic cycle.
Benzimidazole fragment containing Mn-complex catalyzed hydrosilylation of ketones and nitriles
Ganguli, Kasturi,Mandal, Adarsha,Sarkar, Bidisha,Kundu, Sabuj
, (2020/08/13)
The synthesis of a new bidentate (NN)–Mn(I) complex is reported and its catalytic activity towards the reduction of ketones and nitriles is studied. On comparing the reactivity of various other Mn(I) complexes supported by benzimidazole ligand, it was observed that the Mn(I) complexes bearing 6-methylpyridine and benzimidazole fragments exhibited the highest catalytic activity towards monohydrosilylation of ketones and dihydrosilylation of nitriles. Using this protocol, a wide range of ketones were selectively reduced to the corresponding silyl ethers. In case of unsaturated ketones, the chemoselective reduction of carbonyl group over olefinic bonds was observed. Additionally, selective dihydrosilylation of several nitriles were also achieved using this complex. Mechanistic investigations with radical scavengers suggested the involvement of radical species during the catalytic reaction. Stoichiometric reaction of the Mn(I) complex with phenylsilane revealed the formation of a new Mn(I) complex.
Transition metal-free catalytic reduction of primary amides using an abnormal NHC based potassium complex: Integrating nucleophilicity with Lewis acidic activation
Bhunia, Mrinal,Sahoo, Sumeet Ranjan,Das, Arpan,Ahmed, Jasimuddin,Sreejyothi,Mandal, Swadhin K.
, p. 1848 - 1854 (2020/03/03)
An abnormal N-heterocyclic carbene (aNHC) based potassium complex was used as a transition metal-free catalyst for reduction of primary amides to corresponding primary amines under ambient conditions. Only 2 mol% loading of the catalyst exhibits a broad substrate scope including aromatic, aliphatic and heterocyclic primary amides with excellent functional group tolerance. This method was applicable for reduction of chiral amides and utilized for the synthesis of pharmaceutically valuable precursors on a gram scale. During mechanistic investigation, several intermediates were isolated and characterized through spectroscopic techniques and one of the catalytic intermediates was characterized through single-crystal XRD. A well-defined catalyst and isolable intermediate along with several stoichiometric experiments, in situ NMR experiments and the DFT study helped us to sketch the mechanistic pathway for this reduction process unravelling the dual role of the catalyst involving nucleophilic activation by aNHC along with Lewis acidic activation by K ions.
