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heterocyclic amines

Hyowon Seo, Matthew H Katcher, Timothy F Jamison
Although carbon dioxide (CO2) is highly abundant, its low reactivity has limited its use in chemical synthesis. In particular, methods for carbon-carbon bond formation generally rely on two-electron mechanisms for CO2 activation and require highly activated reaction partners. Alternatively, radical pathways accessed via photoredox catalysis could provide new reactivity under milder conditions. Here we demonstrate the direct coupling of CO2 and amines via the single-electron reduction of CO2 for the photoredox-catalysed continuous flow synthesis of α-amino acids...
May 2017: Nature Chemistry
Hiroyuki Watanabe, Masataka Hirose, Kazuo Tanaka, Yoshiki Chujo
This communication describes the transformation of a non-emissive heterocycle into a luminophore via modulation of molecular orbitals by employing a dialkylamine-substituted pentaazaphenalene (A5AP) skeleton. It was presumed that the introduction of the amine group changed the symmetry-forbidden HOMO-LUMO (H-L) transition to an allowed one. According to optical measurements and theoretical calculations, the H-L transition was turned into the symmetry-allowed one because of the lone pair on the nitrogen atom in the dialkylamine substituent...
April 21, 2017: Chemical Communications: Chem Comm
Zhi-Yun Liu, Zhi-Hui Wen, Xiao-Chen Wang
B(C6 F5 )3 has been found to be an effective catalyst for reduction of pyridines and other electron-deficient N-heteroarenes with hydrosilanes (or hydroboranes) and amines as the reducing reagents. The success of this development hinges upon the realization of a cascade process of dearomative hydrosilylation (or hydroboration) and transfer hydrogenation. The broad functional-group tolerance (e.g. ketone, ester, unactivated olefins, nitro, nitrile, heterocycles, etc.) implies high practical utility.
April 18, 2017: Angewandte Chemie
Gema Guedes de la Cruz, Barbora Svobodova, Michaela Lichtenegger, Oleksandra Tiapko, Klaus Groschner, Toma Glasnov
Upon controlled microwave heating and using cyanuric chloride as a coupling reagent, an efficient amidation procedure for the synthesis of 1,3-dihydro-2H-benzo[d]imidazol-2-one-based agonists of TRPC3/6 ion channels has been developed. Compared to the few conventional protocols, a drastic reduction in processing time from ca. 2 days down to 10 minutes was achieved accompanied by significantly improved product yields. The robustness of the method was confirmed by 18 additional examples including aromatic, aliphatic, and heterocyclic amines and acids...
April 2017: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry
Guangrong Meng, Peng Lei, Michal Szostak
The first general method is reported for transamidation of secondary carboxamides catalyzed by Pd-NHC (NHC = N-heterocyclic carbene) complexes. Commercially available, air- and moisture-stable (NHC)Pd(R-allyl)Cl complexes can effect C-N cross-coupling of a wide range of N-Boc and N-Ts amides, obtained by selective amide N-functionalization, with non-nucleophilic anilines and sterically hindered amines in very good yields. The first use of versatile Pd-NHC complexes as catalysts is represented for transition-metal-catalyzed C(acyl)-N amination of amides by N-C activation...
April 11, 2017: Organic Letters
Ming Shang, Ming-Ming Wang, Tyler G Saint-Denis, Ming-Hong Li, Hui-Xiong Dai, Jin-Quan Yu
One long-standing issue in directed C-H functionalization is that either nitrogen or sulfur atoms present in heterocyclic substrates may bind preferentially to a transition-metal catalyst rather than to the desired directing group. This competitive binding has largely hindered the application of C-H functionalization in late-stage heterocycle drug discovery. Reported here is the use of an oxazoline-based directing group capable of overriding the poisoning effect of a wide range of heterocycle substrates. The potential use of this directing group in pharmaceutical drug discovery is illustrated by diversification of Telmisartan (an antagonist for the angiotensin II receptor) through copper-mediated C-H amination, hydroxylation, thiolation, arylation, and trifluoromethylation...
April 10, 2017: Angewandte Chemie
Radim Hrdina, Marta Larrosa, Christian Logemann
We have developed a one-step procedure to a variety of chiral lipophilic and conformationally rigid amines and heterocycles by decarboxylation of adamantane-oxazolidine-2-one. Triflic acid or aluminum triflate promote the addition of diverse nucleophiles to oxazolidine-2-one moiety accompanied by the release of carbon dioxide. The resulting amine or heterocycle is then protonated/metalated by the catalyst (promotor). Additionally, the starting racemic material, adamantane-oxazolidine-2-one, was resolved into single enantiomers using a chiral auxiliary to access enantio-enriched products and to study the racemization pathway of chiral 1,2-disubstituted adamantane derivatives...
April 7, 2017: Journal of Organic Chemistry
Emanuel Hernández-Núñez, Hugo Tlahuext, Rosa Moo-Puc, Diego Moreno, María Ortencia González-Díaz, Gabriel Navarrete Vázquez
Parasitic diseases are a public health problem affecting millions of people worldwide. One of the scaffolds used in several drugs for the treatment of parasitic diseases is the benzimidazole moiety, a heterocyclic aromatic compound. This compound is a crucial pharmacophore group and is considered a privileged structure in medicinal chemistry. In this study, the benzimidazole core served as a model for the synthesis of a series of 2-(2-amino-5(6)-nitro-1H-benzimidazol-1-yl)-N-arylacetamides 1-8 as benznidazole analogues...
April 4, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Rahul B Sonawane, Nishant K Rasal, Sangeeta V Jagtap
A highly efficient protocol of Ni(II) metal complex, [Ni(quin)2], catalyzing N-formylation and N-acylation of amines with moderate to excellent yields, using N,N-dimethylformamide and N,N-dimethylacetamide in the presence of imidazole, is described here. The protocol shows broad substrate scope for aliphatic, aromatic, and heterocyclic amines.
April 4, 2017: Organic Letters
Monika Gibis, Jochen Weiss
Microcrystalline cellulose (MCC) or carboxymethyl cellulose (CMC) can be used as fat replacers; both are nondigestible fibers. As water-holding compounds, the impact of added CMC or MCC was studied concerning the formation of heterocyclic amines (HAAs). Low-fat patties with 0.5-3% MCC/CMC were prepared using 90% of beef and 10% of an aqueous fiber dispersion and were determined for HAA-levels after grilling. The HAAs in patties containing CMC(MCC) were found in the following concentrations; MeIQx (2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline) 0...
August 15, 2017: Food Chemistry
Ya Zhou, Zhiqing Liu, Tingting Yuan, Jianbin Huang, Chenjiang Liu
A facile, green, and efficient method for the direct oxidative amination of benzoxazoles using heterocyclic ionic liquid as catalyst has been developed. The reaction proceeded smoothly at room temperature and gave the desirable 2-aminobenzoxazoles with good to excellent yields (up to 97%). The catalyst 1-butylpyridinium iodide can be easily recycled and reused with similar efficacies for at least four cycles.
April 2, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Hongxian Li, Xiangmin Li, Yang Yu, Jianjun Li, Yuan Liu, Hao Li, Wei Wang
A metal-free catalytic strategy for the facile synthesis of biologically relevant molecular architectures indolizines and imidazopyridines has been developed. The process is promoted by amine and N-heterocyclic carbene (NHC) relay catalysis via Michael addition-[3 + 2] fusion of simple azaarenes and α,β-unsaturated aldehydes. The preparative power is demonstrated in the synthesis of anxiolytic drug saripidem via two simple one-pot operations with overall 45% yield.
March 31, 2017: Organic Letters
Jingjing Li, Pengxiang Zhang, Min Jiang, Haijun Yang, Yufen Zhao, Hua Fu
A novel, simple, and practical visible-light-mediated intramolecular α-C(sp(3))-H imination of tertiary aliphatic amines containing β-O-aryl oximes leading to N-heterocycles has been developed. The reaction was performed well at rt with tolerance of some functional groups. Importantly, the selective C-H functionalization did not require added catalyst, oxidant, additive, acid, and base; visible light was the sole requirement.
March 31, 2017: Organic Letters
M I D Mardjan, S Perie, J-L Parrain, L Commeiras
A versatile copper(i)-catalyzed cascade multicomponent reaction strategy between readily available (Z)-3-iodoacrylic acids, terminal alkynes, and primary amines is reported, leading to a great diversity of complex heterocyclic backbones based on biorelevant indole/lactam scaffolds.
April 11, 2017: Organic & Biomolecular Chemistry
Wrickban Mazumdar, Navendu Jana, Bryant T Thurman, Donald J Wink, Tom G Driver
A new reactivity pattern of Rh2(II)-N-arylnitrenes was discovered that facilitates the synthesis of medium-sized N-heterocycles from ortho-cyclobutanol-substituted aryl azides. The key ring-expansion step of the catalytic cycle is both chemoselective and stereospecific. Our mechanistic experiments implicate the formation of a rhodium N-arylnitrene catalytic intermediate and reveal that sp(3) C-H bond amination of this electrophilic species is competitive with the ring-expansion process.
March 29, 2017: Journal of the American Chemical Society
Kirsty Adams, Anthony K Ball, James Birkett, Lee Brown, Ben Chappell, Duncan M Gill, P K Tony Lo, Nathan J Patmore, Craig R Rice, James Ryan, Piotr Raubo, Joseph B Sweeney
Heterocyclic architectures offer powerful creative possibilities to a range of chemistry end-users. This is particularly true of heterocycles containing a high proportion of sp(3)-carbon atoms, which confer precise spatial definition upon chemical probes, drug substances, chiral monomers and the like. Nonetheless, simple catalytic routes to new heterocyclic cores are infrequently reported, and methods making use of biomass-accessible starting materials are also rare. Here, we demonstrate a new method allowing rapid entry to spirocyclic bis-heterocycles, in which inexpensive iron(III) catalysts mediate a highly stereoselective C-C bond-forming cyclization cascade reaction using (2-halo)aryl ethers and amines constructed using feedstock chemicals readily available from plant sources...
April 2017: Nature Chemistry
Yan He, Fang Wang, Xinying Zhang, Xuesen Fan
A novel and efficient synthesis of tetrahydropyridine (THP)-, dihydropyrrole (DHP)-, or tetrahydroazepine (THA)-3-carboxylates via cascade reactions of inactivated cyclic amines with CO and alcohols is presented. To our knowledge, this should be the first example in which functionalized N-heterocycles were prepared directly from Pd-catalyzed C(sp(3))-H dehydrogenation and C(sp(2))-H carbonylation of saturated cyclic amines. Moreover, the DHP-3-carboxylates thus obtained could readily undergo an oxidative aromatization to give pyrrole-3-carboxylates by using O2 as a green oxidant...
March 24, 2017: Chemical Communications: Chem Comm
Bas de Bruin, Petrus F Kuijpers, Martijn J Tiekink, Willem B Breukelaar, Daniël L J Broere, Nicolaas P van Leest, Jarl Ivar van der Vlugt, Joost N H Reek
Cobalt porphyrin catalysed intramolecular ring-closing C-H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air and moisture stable catalyst. Kinetic studies of the reaction in combination with DFT calculations reveal a metallo-radical-type mechanism involving rate limiting azide activation to form the key cobalt(III)-nitrene radical intermediate...
March 23, 2017: Chemistry: a European Journal
Gunnar Hall, Susanne Alenljung, Ulla Forsgren-Brusk
PURPOSE: The purpose of this study was to identify key odorants in used disposable absorbent incontinence products. DESIGN: Descriptive in vitro study SUBJECTS AND SETTING:: Samples of used incontinence products were collected from 8 residents with urinary incontinence living in geriatric nursing homes in the Gothenburg area of Sweden. Products were chosen from a larger set of products that had previously been characterized by descriptive odor analysis. METHODS: Pieces of the used incontinence products were cut from the wet area, placed in glass bottles, and kept frozen until dynamic headspace sampling of volatile compounds was completed...
March 22, 2017: Journal of Wound, Ostomy, and Continence Nursing
Emilia S Streng, Darren S Lee, Michael W George, Martyn Poliakoff
The use of γ-Al2O3 as a heterogeneous catalyst in scCO2 has been successfully applied to the amination of alcohols for the synthesis of N-alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self-optimising reactor, resulting in moderate to high yields of the target products. Carrying out the reaction in scCO2 was shown to be beneficial, as higher yields were obtained in the presence of CO2 than in its absence. A surprising discovery is that, in addition to cyclic amines, cyclic ureas and urethanes could be synthesised by incorporation of CO2 from the supercritical solvent into the product...
2017: Beilstein Journal of Organic Chemistry
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