54436-58-7Relevant academic research and scientific papers
Hydroamination/cyclization of aminoalkenes using cationic zirconocene and titanocene catalysts
Gribkov, Denis V.,Hultzsch, Kai C.
, p. 5542 - 5546 (2004)
Alternative catalysts: The hydroamination of nonactivated double bonds has been the domain of rare-earth-metal catalysts. Now alkyl zirconocene and titanocene cations, which are readily prepared from commercially available precursors, are shown to be active catalysts in the hydroamination/cyclization of secondary aminoalkenes to give tertiary pyrrolidines and piperidines.
N-Cyanation of Primary and Secondary Amines with Cyanobenzio-doxolone (CBX) Reagent
Chen, Zimin,Yuan, Weiming
supporting information, p. 14836 - 14840 (2021/09/30)
An efficient electrophilic N-cyanation of amines with a stable and less-toxic cyanobenziodoxole reagent towards the synthesis of cyanamides is disclosed. This synthetically practicable strategy allows the construction of a wide variety of cyanamides under very mild and simple conditions with a broad functional group compatibility, and showcases a huge potential in late-stage modification of complex molecules.
Modular Entry to Functionalized Tetrahydrobenzo[ b]azepines via the Palladium/Norbornene Cooperative Catalysis Enabled by a C7-Modified Norbornene
Dong, Guangbin,Liu, Xin,Wang, Jianchun
supporting information, p. 9991 - 10004 (2021/07/19)
Tetrahydrobenzo[b]azepines (THBAs) are commonly found in many bioactive compounds; however, the modular preparation of functionalized THBAs remains challenging to date. Here, we report a straightforward method to synthesize THBAs directly from simple aryl iodides via palladium/norbornene (Pd/NBE) cooperative catalysis. Capitalizing on an olefin-tethered electrophilic amine reagent, an ortho amination followed by 7-exo-trig Heck cyclization furnishes the seven-membered heterocycle. To overcome the difficulty with ortho-unsubstituted aryl iodide substrates, we discovered a unique C7-bromo-substituted NBE (N1) to offer the desired reactivity and selectivity. In addition to THBAs, synthesis of other benzo-seven-membered ring compounds can also be promoted by N1. Combined experimental and computational studies show that the C7-bromo group in N1 plays an important and versatile role in this catalysis, including promoting β-carbon elimination, suppressing benzocyclobutene formation, and stabilizing reaction intermediates. The mechanistic insights gained could guide future catalyst design. The synthetic utility has been demonstrated in a streamlined synthesis of tolvaptan and forming diverse pharmaceutically relevant THBA derivatives. Finally, a complementary and general catalytic condition to access C6-substituted THBAs from ortho-substituted aryl iodides has also been developed.
Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines
Hasegawa, Eietsu,Nagakura, Yuto,Izumiya, Norihiro,Matsumoto, Keisuke,Tanaka, Tsukasa,Miura, Tomoaki,Ikoma, Tadaaki,Iwamoto, Hajime,Wakamatsu, Kan
, p. 10813 - 10825 (2018/07/30)
A visible light promoted process for desulfonylation of N-sulfonylamides and -amines has been developed, in which 1,3-dimethyl-2-hydroxynaphthylbenzimidazoline (HONap-BIH) serves as a light absorbing, electron and hydrogen atom donor, and a household white light-emitting diode serves as a light source. The process transforms various N-sulfonylamide and -amine substrates to desulfonylated products in moderate to excellent yields. The observation that the fluorescence of 1-methyl-2-naphthoxy anion is efficiently quenched by the substrates suggests that the mechanism for the photoinduced desulfonylation reaction begins with photoexcitation of the naphthoxide chromophore in HONap-BIH, which generates an excited species via intramolecular proton transfer between the HONap and BIH moieties. This process triggers single electron transfer to the substrate, which promotes loss of the sulfonyl group to form the free amide or amine. The results of studies employing radical probe substrates as well as DFT calculations suggest that selective nitrogen-sulfur bond cleavage of the substrate radical anion generates either a pair of an amide or amine anion and a sulfonyl radical or that of an amidyl or aminyl radical and sulfinate anion, depending on the nature of the N-substituent on the substrate. An intermolecular version of this protocol, in which 1-methyl-2-naphthol and 1,3-dimethyl-2-phenylbenzimidazoline are used concomitantly, was also examined.
Use of (cyclopentadienone)iron tricarbonyl complexes for c-n bond formation reactions between amines and alcohols
Brown, Thomas J.,Cumbes, Madeleine,Diorazio, Louis J.,Clarkson, Guy J.,Wills, Martin
, p. 10489 - 10503 (2018/05/31)
The application of a series of (cyclopentadienone)iron tricarbonyl complexes to "borrowing hydrogen" reactions between amines and alcohols was completed in order to assess their catalytic activity. The electronic variation of the aromatic groups flanking the C?O of the cyclopentadienone influenced the efficiency of the reactions; however, in other cases, the Kn?lker catalyst 1, containing trimethylsilyl groups flanking the cyclopentadienone ketone, gave the best results. In some cases, the change of the ratio of amine to alcohol improves the conversion significantly. The application of iron catalysts to the synthesis of a range of amines, including unsaturated amines, was investigated.
Regioselective copper(II)-mediated bromoamination of unfunctionalized olefins: An efficient route to N-heterocyclic compounds
Liu, Gong-Qing,Ding, Zhen-Ying,Zhang, Li,Li, Ting-Ting,Li, Lin,Duan, Lili,Li, Yue-Ming
supporting information, p. 2303 - 2310 (2014/07/21)
Bromoamination of unfunctionalized olefins was realized under mild conditions using copper(II) bromide (CuBr2) as both reaction promoter and bromine source. The reactions could be carried out under open air at ambient temperature, and both N-alkylated and N-tosylated substrates could be converted to the corresponding N-heterocyclic compounds in high regioselectivity and good isolated yields. A variety of biologically important structures could be obtained via subsequent nucleophilic substitution reactions.
Ti-mediated intramolecular cyclopropanation of N-alkenyl thioamides: Scope and mechanistic study
Hermant, Fabien,Nicolas, Emmanuel,Six, Yvan
supporting information, p. 3924 - 3930 (2014/06/09)
Although thioamides generally undergo a reductive alkylation process when they are treated with a Grignard reagent in the presence of Ti(OiPr) 4, substrates fitted with a but-3-enyl substitution at the nitrogen atom are shown to be converted into bicyclic aminocyclopropanes. These reactions are compared with the similar cyclisations of the corresponding carboxylic amide substrates. A mechanistic study is provided. Coincidently, new reagent systems are identified for the mediation of the same transformation.
Ring-closing metathesis of vinyl fluorides towards α-fluorinated α,β-unsaturated lactams and lactones
Marhold, Michael,Stillig, Christian,Fr?hlich, Roland,Haufe, Günter
supporting information, p. 5777 - 5785 (2014/10/15)
Ring-closing olefin metathesis reactions (RCM) using Grubbs II or Hoveyda's catalysts have been applied to a series of N-alkenyl-N-benzyl-α-fluoroacrylamides. α-Fluoro-α,β-unsaturated γ- or δ-lactams incorporating a fluorinated double bond were obtained in moderate to good yields, depending on the nature of substituents on the benzyl ring. The corresponding seven- and eight-membered lactams were not formed under similar conditions. When the N-benzyl group was replaced by an N-tosyl group, the corresponding ε-lactam was also formed in 38% yield. When N-(2-fluoroallyl) derivatives were used instead of fluoroacryloyl derivatives, six-, seven-, and eight-membered N-heterocycles were obtained in low yields. This method was also used to synthesize fluorinated α,β-unsaturated analogues of pyrrolizidine and indolizidine alkaloids from prolinol, and also to synthesize N-benzyl-3-fluoroquinolone in three steps from commercially available 2-vinylaniline in 44% overall yield. Also 3-fluorocoumarin and 3-fluorochromene were prepared from ovinylphenol, and 3-fluoro-benzoxepine was available from o-allylphenol.
Reductive alkylation of thioamides with Grignard reagents in the presence of Ti(O i Pr)4: Insight and extension
Hermant, Fabien,Urbaska, Ewelina,Seizilles De Mazancourt, Sarah,Maubert, Thomas,Nicolas, Emmanuel,Six, Yvan
supporting information, p. 5643 - 5653 (2015/02/19)
The reductive alkylation of thioamides by Grignard reagents in the presence of Ti(OiPr)4 is the subject of a study involving 20 different substrates. The influence of various parameters has been evaluated, showing notably that the yields of this moderately efficient process can be improved in several cases by applying a slow addition of the Grignard reagent. The results presented in this contribution also provide new insight into the reactivity of the proposed key intermediates, namely, a metalated iminium species and, ultimately, an α-metalated amine. Interestingly, by control of the temperature and the amount of Grignard reagent engaged, the reaction can be directed toward the selective formation of the former titanium intermediate complex. This represents an extension of the original method, allowing the synthesis of various previously inaccessible substituted amines by subsequent addition of a nucleophilic reagent. This role can be played not only by organomagnesium compounds but also by alkyllithium reagents, alkyltitanium(IV) complexes, and lithium aluminum hydride. The properties of the α-metalated amine final intermediate have also been explored, demonstrating that this complex is a poor nucleophile but can act as a radical precursor, which is especially evidenced when the resulting radical species are stabilized. Overall, this chemistry thus proves unexpectedly rich and can plausibly lay the basis for the development of new applications in the future.
Cooperative catalysis with aldehydes and copper: Development and application in aerobic oxidative C-H amination at room temperature
Xie, Yinjun,Qian, Bo,Xie, Pan,Huang, Hanmin
, p. 1315 - 1322 (2013/06/27)
A conceptually new cooperative catalytic system via a synergistic combination of aldehyde and copper catalysis has been established based on systemic mechanistic studies. This new cooperative catalysis has been successfully applied in the direct aerobic oxidative C-H amination of azoles at room temperature, which was previously realized under harsh conditions. Mechanistic studies including isotopic labeling experiments and kinetic isotope effect (KIE) experiments support a reaction pathway that involves formation of an aminal, hydrolysis of the aminal to generate the copper-amide species, subsequent C-H amination and re-oxidation of copper(I) to copper(II) by oxygen. It not only provides an efficient method to realize the oxidative C-H amination of benzoxazoles with free amines at room temperature, but also paves the way for establishing new C-N bond formation reactions by using this efficient cooperative catalysis. Copyright
