3858-78-4Relevant articles and documents
Direct Amidation of Esters by Ball Milling**
Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
supporting information, p. 21868 - 21874 (2021/09/02)
The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
Base-Catalyzed Hydrosilylation of Nitriles to Amines and Esters to Alcohols
Clarke, Joshua A.,Nikonov, Georgii I.,van der Est, Art
supporting information, p. 4434 - 4439 (2021/08/30)
Base-catalyzed hydrosilylation of nitriles to amines and esters to silylated alcohols is reported. This protocol tolerates electron-rich and electron-neutral olefins and works in the presence of basic functional groups (e. g. tertiary amines) but fails for acidic substrates, such as phenols and NH anilines. This catalytic system does not tolerate carbonyl groups, such as aldehydes, ketones, esters and carbamides, which are reduced to corresponding alcohols and amines. With the exact amount of silane, esters can be selectively reduced in the presence of nitriles, but the selectivity drops for the pairs ester/carboxamide and carboxamide/nitrile. Through competition experiments, the following preference in functional group reactivity was determined: ester > carboxamide > nitrile.
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; 0017-0020, (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.
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.
Primary amides to amines or nitriles: A dual role by a single catalyst
Das, Hari S.,Das, Shyamal,Dey, Kartick,Singh, Bhagat,Haridasan, Rahul,Das, Arpan,Ahmed, Jasimuddin,Mandal, Swadhin K.
supporting information, p. 11868 - 11871 (2019/10/11)
We report a manganese-catalyzed hydrosilylative reduction of various primary amides to amines (25 examples). On simple modification of the reaction conditions such as in the presence of a catalytic amount of secondary amide, the same catalyst can transform the primary amides into intermediate nitrile compounds (16 examples) in excellent yields. This is the first example where such a controlled catalytic transformation of primary amides to amines or nitriles with a single catalyst has been demonstrated.
Chemoselective Synthesis of Amines from Ammonium Hydroxide and Hydroxylamine in Continuous Flow
Audubert, Clément,Bouchard, Alexanne,Mathieu, Gary,Lebel, Hélène
, p. 14203 - 14209 (2019/01/21)
The chemoselective amination of alkyl bromides and chlorides with aqueous ammonia and hydroxylamine was achieved in continuous flow to produce primary ammonium salts and hydroxylamines in high yields. An in-line workup was designed to isolate the corresponding primary amine, which was also telescoped in further reactions, such as acylation and Paal-Knorr pyrrole synthesis. Monosubstituted epoxides are also compatible with the reaction conditions.
Ru-Catalyzed Transfer Hydrogenation of Nitriles, Aromatics, Olefins, Alkynes and Esters
Alshakova, Iryna D.,Gabidullin, Bulat,Nikonov, Georgii I.
, p. 4860 - 4869 (2018/10/02)
This paper reports the preparation of new ruthenium(II) complexes supported by a pyrazole-phosphine ligand and their application to transfer hydrogenation of various substrates. These Ru complexes were found to be efficient catalysts for the reduction of nitriles and olefins. Heterocyclic compounds undergo transfer hydrogenation with good to moderate yields, affording examples of unusual hydrogenation of all-carbon-rings. Internal alkynes with bulky substituents show selective reduction to olefins with the unusual E–selectivity. Esters with strong electron-withdrawing groups can be reduced to the corresponding alcohols, if ethanol is used as the solvent. Possible mechanisms of hydrogenation and olefin isomerization are suggested on the basis of kinetic studies and labelling experiments.
Cobalt-Catalyzed and Lewis Acid-Assisted Nitrile Hydrogenation to Primary Amines: A Combined Effort
Tokmic, Kenan,Jackson, Bailey J.,Salazar, Andrea,Woods, Toby J.,Fout, Alison R.
supporting information, p. 13554 - 13561 (2017/10/05)
The selective hydrogenation of nitriles to primary amines using a bench-stable cobalt precatalyst under 4 atm of H2 is reported herein. The catalyst precursor was reduced in situ using NaHBEt3, and the resulting Lewis acid formed, BEt3, was found to be integral to the observed catalysis. Mechanistic insights gleaned from para-hydrogen induced polarization (PHIP) transfer NMR studies revealed that the pairwise hydrogenation of nitriles proceeded through a Co(I/III) redox process.
HIGHLY TUNABLE COLLOIDAL PEROVSKITE NANOPLATELETS
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Paragraph 0074; 0075; 0076, (2017/11/29)
Colloidal perovskite nanoplatelets can provide a material platform, with tunability extending from the deep UV, across the visible, into the near-IR. The high degree of spectral tunability can be achieved through variation of the cation, metal, and halide composition as well as nanoplatelet thickness.
