5455-87-8Relevant academic research and scientific papers
Stereoselective synthesis of a new enantiopure tricyclic β-lactam derivative via a tricarbonyl(η6-arene)chromium(0) complex
Del Buttero, Paola,Baldoli, Clara,Molteni, Giorgio,Pilati, Tullio
, p. 1927 - 1941 (2000)
The tricyclic β-lactam 5 has been synthesized both in racemic and enantiopure form starting from the enantiomerically pure tricarbonylchromium(0) complex 1. The synthetic sequence involves the stereoselective [2+2] cycloaddition of 1 with acetoxyacetylket
Au(I) Catalyzed Synthesis of Densely Substituted Pyrazolines and Dihydropyridines via Sequential Aza-Enyne Metathesis/6π-Electrocyclization
Sugimoto, Kenji,Kosuge, Shuto,Sugita, Takae,Miura, Yuka,Tsuge, Kiyoshi,Matsuya, Yuji
supporting information, p. 3981 - 3985 (2021/05/26)
A gold(I) autotandem catalysis protocol is reported for the de novo synthesis of densely substituted pyrazolines and dihydropyridines from the corresponding imine derivatives in a highly regioselective fashion via a one-pot aza-enyne metathesis/6π-electrocyclization sequence. The substituents on the nitrogen atom of the imine perfectly control the reaction pathways from the pivotal 1-azabutadiene intermediate; thus, carbazates were converted into pyrazolines via 6π-electrocyclization of α,β-unsaturated hydrazones, while aryl imines provided dihydropyridines via 6π-electrocyclization of 3-azahexatrienes.
Nanomagnetic catalysis (Fe3O4@S–TiO2): a novel magnetically nano catalyst for the synthesis of new highly substituted tetrahydropyridine derivatives under solvent-free conditions
Nezami, Zahra,Eshghi, Hossein
, p. 1997 - 2008 (2021/01/20)
A novel nanomagnetic catalyst (Fe3O4@S–TiO2) was prepared by the hydrothermal method. At the first, Fe3O4 nanoparticles were synthesized, then iron oxide nanoparticles (IONPs) were dispersed in ethano
New compounds for a good old class: Synthesis of two Β-lactam bearing cephalosporins and their evaluation with a multidisciplinary approach
Vigliotta, Giovanni,Giordano, Deborah,Verdino, Anna,Caputo, Ivana,Martucciello, Stefania,Soriente, Annunziata,Marabotti, Anna,De Rosa, Margherita
, (2020/01/22)
Antimicrobial resistance is spreading massively in the world and is becoming one of the main health threats of the 21st century. One of the possible strategies to overcome this problem is to modify the known classes of antibiotics in a rational way, with the aim of tuning their efficacy. In this paper, we present the synthesis and the evaluation of the biological activity of a series of two β-lactam bearing cephalosporin derivatives, in which an additional isolated azetidinone ring, bearing different substituents, is joined to the classical cephalosporanic nucleus by a chain of variable length. A computational approach has been also applied in order to predict the molecular interactions between some representative derivatives and selected penicillin-binding proteins, the natural targets of β-lactam antibiotics. All these derivatives are active against Gram-positive bacteria, with MIC100 comparable or even better than that of the reference antibiotic ceftriaxone, and show no or very low cytotoxic activity on different cell lines. Overall, these molecules appear to be able to exert their activity in particular against microorganisms belonging to some of the species more involved in the development of multidrug resistance.
Observation of the complex spectra for the supramolecular system involving silver nanoparticles-biaryl Schiff bases containing the nitro group
Cao, Chao-Tun,Cheng, Shi-Mao,Cao, Chenzhong
, (2020/02/11)
A series of biaryl Schiff bases containing the nitro groups, 4-XArCH═NArNO2-4′ (XBANO2-4′) and 4-NO2ArCH═NArY-4′ (4-NO2BAY), were synthesized. Also, the fish sperm DNA (fsDNA) and silver nanoparticles (AgNPs) solutions were prepared. By mixing these compounds with fsDNA or AgNPs solution and determining the ultraviolet absorption spectra of the mixture solutions, an interesting phenomenon was found: a new absorption peak λmax,lim appeared in the (XBANO2-4′)-AgNPs solution, which was longer than the wavelength of λmax of XBANO2-4′ solution. The new absorption peak in the (XBANO2-4′)-AgNPs solution was the complex spectrum originating from the electron transfer between XBANO2-4′ and AgNPs. Whereas this phenomenon was not observed in the (4-NO2BAY)-AgNPs solutions, a quantitative correlation analysis was carried out with the measured spectral data, and the results show that the wave number νmax,lim of the λmax,lim is mainly affected by the excited-state substituent constant (Formula presented.) rather than the ground Hammett constant σ of the X group. The redshift magnitude Δνmax,WSL, namely, Δνmax,WSL = (1/λmax) ? (1/λmax,lim), of the wavelength λmax,lim is related to the highest occupied molecular orbital and lowest unoccupied molecular orbital of XBANO2-4′. The discovery of this new phenomenon is helpful to understanding the interaction between AgNPs-organic compound supramolecular systems.
Enantioselective Direct anti-Selective Mannich-type Reactions Catalyzed by 3-Pyrrolidinecarboxylic Acid in the Presence of Potassium Carbonate: Addition of Potassium Carbonate Improves Enantioselectivities
Garg, Yuvraj,Tanaka, Fujie
supporting information, p. 4542 - 4546 (2020/06/08)
Mannich-type reactions of cyclohexanone and related six-membered-ring ketones with N-p-methoxyphenyl-protected imines of arylaldehydes catalyzed by 3-pyrrolidinecarboxylic acid in the presence of K2CO3 that afford anti-isomers of the Mannich products with
Simple synthesis of the novel Cu-MOF catalysts for the selective alcohol oxidation and the oxidative cross-coupling of amines and alcohols
Ghamari Kargar, Pouya,Aryanejad, Sima,Bagherzade, Ghodsieh
, (2020/09/11)
A novel porous metal–organic framework {Cu2(bbda)0.5(Hbbda)1.5(OAc)1.5.8H2O} (UoB-5) was synthesized under ultrasound irradiation by employing a new Schiff base ligand H2bbda (4,4'(1,4-phenylene bis (azanylylidene)) bis (methanylylidene))dibenzoic acid) and was fully characterized. The microporous nature of UoB-5 was confirmed by gas-sorption measurements. This framework acted as a highly effective heterogeneous catalyst for the alcohol oxidation reaction with tert-butyl hydroperoxide (t-BuOOH) as an oxidant. The presence of coordinatively unsaturated metal sites in UoB-5 could be the reason for high performance in this reaction. Furthermore, using the long linker with the free -NC group and uncoordinated -N atom on the wall of the pores created UoB-5 an excellent candidate for the catalytic activities without activation of the framework. It was confirmed with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from benzyl alcohols and anilines. Eventually, the new Cu-MOF (UoB-5) could be an alternative catalyst as a more economically favorable and environmentally friendly in the catalysis field.
Time-Dependent Switching of Constitutional Dynamic Libraries and Networks from Kinetic to Thermodynamic Distributions
He, Meixia,Lehn, Jean-Marie
supporting information, p. 18560 - 18569 (2019/11/21)
The distribution of the constituents of a constitutional dynamic library (CDL) may undergo time-dependent changes as a function of the kinetics of the processes generating the CDL from its components. Thus, the constitutional dynamic network (CDN) representing the connections between the constituents changes from a kinetic distribution to the thermodynamic one as a function of time. We investigated the behavior of dynamic covalent libraries (DCLs) of four constituents generated by reversible formation of C═N bonds between four components, 2 aldehydes and 2 amino compounds, both in absence and in the presence of metal cations. The associated [2 × 2] networks underwent time-dependent changes from the initial kinetic distribution to the final thermodynamic one, involving an orthogonal switch from one diagonal to the other diagonal of the square [2 × 2] network leading to a very large change in distribution. The DCL constituents could be switched from kinetic products (imines) to thermodynamic products (oximes or acylhydrazones) based on the reactivities of the components and the thermodynamic stabilities of the constituents without addition of any external effector, solely on the basis of the intrinsic properties of the self-contained system. Such processes were achieved for purely organic DCLs/CDNs as well as for inorganic ones containing two metal cations, the latter changing from the silver(I) complex of an imine (kinetic product) to the zinc(II) complex of a hydrazone (thermodynamic product). The results bear relationship to out-of-equilibrium systems concerning kinetic behavior in adaptive chemistry.
Heterogeneous Catalysis with Basic Compounds to Achieve the Synthesis and C-N Cleavage of Azetidin-2-ones under Microwave Irradiation
Alcaraz, Yolanda,Cruz, Francisco,De La Cruz, Fabiola N.,Delgado, Francisco,Domínguez, José Manuel,Galván, Adriana,Gomez, Clarisa Villegas,Martínez, Merced,Vázquez, Miguel A.
supporting information, p. 3625 - 3637 (2019/09/30)
The synthesis of azetidin-2-ones with a completely heterogeneous catalysis is reported. The use of basic compounds as solid catalysts allowed for the synthesis of azetidin-2-ones under microwave irradiation without organic additives such as triethylamine. An excellent catalyst for this transformation was Mg-Al hydroxide (MAH). The present methodology offers the advantages of non-hazardous reaction conditions, short reaction times, high yields, and catalyst reusability. Different substitution groups were tested on the imines and acyl chlorides to explore the scope of the reaction. Unconventional N-C4 bond cleavage was detected in azetidin-2-ones. MAH was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM).
A sustainable catalytic enantioselective synthesis of norstatine derivatives
Shi, Taoda,Jing, Changcheng,Qian, Yu,Xu, Xinfang,Alavala, Gopi Krishna Reddy,Lv, Xinxin,Hu, Wenhao
supporting information, p. 9792 - 9798 (2019/12/02)
Norstatine derivatives are of important value in pharmaceutical science. However, their catalytic asymmetric synthesis is rare. We developed a sustainable method via chiral phosphoric acid (CPA)-[Rh(OAc)2]2 co-catalyzed multi-component reactions (MCR) of diazoacetates with alcohol/water and imines. This method allows us to synthesize a library of 45 norstatines with excellent enanotioselectivites and broad substrate scope which includes anti-α-aryl-norstatines 11-1, anti-α-alkyl-norstatines 11-2, syn-α-hydro-norstatines 11-3 and syn-α-aryl-norstatines 11-4. The sustainability of this method lies in the reliable scalability, improved safety, and reusable [Rh(OAc)2]2 catalyst. The synthetic value of norstatine derivatives was demonstrated by preparing oxazolinone 14, ezetimibe analogue 15, and Taxol C-13 chain 16. Mechanistic study reveals that the synergetic catalysis of CPA and [Rh(OAc)2]2 is essential to maintain chemo- and enantioselectivity. Control experiments support the mechanism where the reactions proceed through the trapping of hyper-reactive oxonium ylides with imines. Shortly, we report herein the sustainable catalytic enantioselective synthesis of both syn- and anti-norstatine derivatives. We believe that this method might shed light on the sustainable synthesis of norstatine derivative-based drug candidates.
