7160-02-3Relevant academic research and scientific papers
Stabilization of Azapeptides by Namide···H-NamideHydrogen Bonds
Baruah, Kalpita,Sahariah, Biswajit,Sakpal, Sushil S.,Deka, Jugal Kishore Rai,Bar, Arun Kumar,Bagchi, Sayan,Sarma, Bani Kanta
supporting information, p. 4949 - 4954 (2021/06/28)
An unusual Namide···H-Namide hydrogen bond (HB) was previously proposed to stabilize the azapeptide β-Turns. Herein we provide experimental evidence for the Namide···H-Namide HB and show that this HB endows a stabilization of 1-3 kcal·mol-1 and enforces the trans-cis-Trans (t-c-T) and cis-cis-Trans (c-c-T) amide bond conformations in azapeptides and N-methyl-Azapeptides, respectively. Our results indicate that these Namide···H-Namide HBs can have stabilizing contributions even in short azapeptides that cannot fold to form β-Turns.
Synthesis method of 2-alkynyl substituted indole compound
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Paragraph 0036-0039, (2021/02/02)
The invention discloses a synthesis method of a 2-alkynyl substituted indole derivative. The synthesis method comprises the following steps: under the actions of a rhodium catalyst, a silver additiveand an oxidant, carrying out cyclization reaction on an
Cu(II)-Catalyzed Ortho-C-H Nitration of Aryl Ureas by C-H Functionalization
Wang, Chun-Meng,Tang, Kai-Xiang,Gao, Tian-Hong,Chen, Lin,Sun, Li-Ping
, p. 8315 - 8321 (2018/07/15)
A novel protocol for the aromatic ortho C-H nitration of aryl ureas with Fe(NO3)3·9H2O is developed. The reaction utilizes CuCl2·2H2O as catalyst and p-TSA as additive, showing good functional group tolerance and furnishing the desired products in moderate to excellent yields.
One-pot synthesis of 2,3-difunctionalized indoles: Via Rh(III)-catalyzed carbenoid insertion C-H activation/cyclization
Lv, Honggui,Shi, Jingjing,Wu, Bo,Guo, Yujuan,Huang, Junjun,Yi, Wei
supporting information, p. 8054 - 8058 (2017/10/13)
Reported herein is the first Rh(iii)-catalyzed carbenoid insertion C-H activation/cyclization of N-arylureas and α-diazo β-keto esters. The redox-neutral reaction has the following features: good to excellent yields, broad substrate/functional group tolerance, exclusive regioselectivity, and no need for additional oxidants or additives, which render this methodology as a more efficient and versatile alternative to the existing methods for the synthesis of 2,3-difunctionalized indoles.
Cationic Pd(II)-catalyzed C-H activation/cross-coupling reactions at room temperature: Synthetic and mechanistic studies
Nishikata, Takashi,Abela, Alexander R.,Huang, Shenlin,Lipshutz, Bruce H.
supporting information, p. 1040 - 1064 (2016/07/06)
Cationic palladium(II) complexes have been found to be highly reactive towards aromatic C-H activation of arylureas at room temperature. A commercially available catalyst [Pd(MeCN)4](BF4)2 or a nitrile-free cationic palladium(II) complex generated in situ from the reaction of Pd(OAc)2 and HBF4, effectively catalyzes C-H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates under milder conditions than those previously reported. The nature of the directing group was found to be critical for achieving room temperature conditions, with the urea moiety the most effective in promoting facile coupling reactions at an ortho C-H position. This methodology has been utilized in a streamlined and efficient synthesis of boscalid, an agent produced on the kiloton scale annually and used to control a range of plant pathogens in broadacre and horticultural crops. Mechanistic investigations led to a proposed catalytic cycle involving three steps: (1) C-H activation to generate a cationic palladacycle; (2) reaction of the cationic palladacycle with an aryl iodide, arylboronic acid or acrylate, and (3) regeneration of the active cationic palladium catalyst. The reaction between a cationic palladium(II) complex and arylurea allowed the formation and isolation of the corresponding palladacycle intermediate, characterized by X-ray analysis. Roles of various additives in the stepwise process have also been studied.
Merging C-H activation and alkene difunctionalization at room temperature: A palladium-catalyzed divergent synthesis of indoles and indolines
Manna, Manash Kumar,Hossian, Asik,Jana, Ranjan
supporting information, p. 672 - 675 (2015/03/04)
A palladium-catalyzed 1,2-carboamination through C-H activation at room temperature is reported for the synthesis of 2-arylindoles, and indolines from readily available, inexpensive aryl ureas and vinyl arenes. The reaction initiates with a urea-directed electrophilic ortho palladation, alkene insertion, and ?2-hydride elimination sequences to provide the Fujiwara-Moritani arylation product. Subsequently, aza-Wacker cyclization, and ?2-hydride elimination provide the 2-arylindoles in high yields. Intercepting the common -alkyl-Pd intermediate, corresponding indolines are also achieved. The indoline formation is attributed to the generation of stabilized, cationic -benzyl-Pd species to suppress ?2-hydride elimination.
Copper-catalyzed mild nitration of protected anilines
Hernando, Elier,Castillo, Rafael R.,Rodríguez, Nuria,G?mez Arrayás, Ram?n,Carretero, Juan C.
supporting information, p. 13854 - 13859 (2016/02/18)
A practical copper-catalyzed direct nitration of protected anilines, by using one equivalent of nitric acid as the nitrating agent, has been developed. This procedure features mild reaction conditions, wide structural scope (with regard to both N-protecting group and arene substitution), and high functional-group tolerance. Dinitration with two equivalents of nitric acid is also feasible. Practical and reliable: A Cu-catalyzed selective nitration of para- and ortho-substituted aniline derivatives by using one equivalent of HNO3 has been developed that produces water as the only stoichiometric byproduct (see scheme; PG=protecting group). This method is compatible with strongly electron-deficient substrates, enabling dinitration (by using 2.0 equiv of HNO3). This method allows for a rapid access to relevant nitrogen-containing heterocyclic architectures.
Rhodium(iii)-catalysed aerobic synthesis of highly functionalized indoles from N-arylurea under mild conditions through C-H activation
Kathiravan, Subban,Nicholls, Ian A.
supporting information, p. 14964 - 14967 (2014/12/11)
A Rh(iii) catalysed amino arylation of alkynes using copper as the terminal oxidant for regeneration of the catalytically active species under aerobic conditions is described. This novel C-H activation reaction was applied to the synthesis of a wide range of substituted indoles from N-arylureas.
The vinyl moiety as a handle for regiocontrol in the preparation of unsymmetrical 2,3-aliphatic-substituted indoles and pyrroles
Huestis, Malcolm P.,Chan, Lina,Stuart, David R.,Fagnou, Keith
supporting information; experimental part, p. 1338 - 1341 (2011/04/21)
Rho-Rho-Rho your boat: A rhodium catalyst effects the regioselective oxidative coupling of enynes with N-aryl ureas (X=NR2) and N-vinylacetamides (X=C(O)Me), affording the corresponding 2-alkenylindoles and 2-alkenylpyrroles in good yield. Simple hydrogenation delivers the C2/C3-aliphatic-substituted indole or pyrrole (see scheme).
Accelerating effects of N-aryl-N′,N′-dialkyl ureas on epoxy-dicyandiamide curing system
Liu, Xiang Dong,Kimura, Mika,Sudo, Atsushi,Endo, Takeshi
experimental part, p. 5298 - 5305 (2011/06/21)
This report focuses on epoxy-dicyandiamide (DICY) curing system accelerated by N-aryl-N′,N′-dialkyl urea, aiming at clarifying the accelerating mechanism and the relationship between accelerating effect and molecular structure of the accelerators. Nine N-aryl-N′,N′-dialkyl ureas were synthesized and investigated with measurements of differential scanning calorimetry, thermo gravimetric/differential thermal analysis and NMR spectroscopy. The results revealed that the ureas released the corresponding secondary amines by the thermal dissociation in the presence of epoxide, which led to the formation of tertiary amines that catalyze the addition reaction of DICY to epoxide. Moreover, a tendency that the ureas able to release more compact amines exhibited higher acceleration effects was discovered.
