Top PDF A Two-Step Synthesis of 2-Spiropiperidines

A Two-Step Synthesis of 2-Spiropiperidines

A Two-Step Synthesis of 2-Spiropiperidines

Boc imines used were relatively unstable and so were generated in situ from the N-Boc sulfone precursor 1 (Figure 1). N-Boc sulfone precursors 1 were treated with the Weiler dianion and the resultant N-Boc--amino--ketoesters 2 were isolated. Removal of the N-Boc group was achieved by treatment with HCl in dioxane and the -amino--ketoester·HCl salt was “cracked” in the presence of a ketone 3 with NaHCO 3 , which

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Strategies for the Synthesis of Spiropiperidines - A Review of the Last 10 Years

Strategies for the Synthesis of Spiropiperidines - A Review of the Last 10 Years

A two-step synthesis of 2-spiropiperidines (Scheme 10) was recently presented by Clarke. 18 δ-Amino-β-ketoesters 38 were formed through Mannich addition of the dianion of methyl acetoacetate 37 onto N-Boc imines, which were formed in situ from N-Boc sulfone precursor 36. The N-Boc-δ-amino-β- ketoesters were deprotected with HCl in dioxane and the HCl salts of δ-amino-β-ketoesters 38 were then ‘cracked’ in the presence of a cyclic ketone to give highly functionalised 2- spiropiperidines 39. The synthesis has been shown to proceed with aliphatic, aromatic and heteroaromatic C-6 substituents, with examples of carbocyclic and heterocyclic spirocycles at C- 2. 2-Spiropiperidines are formed in good to excellent yields with moderate diastereoselectivities. The 2-spiropiperidines were further functionalised to generate a small library of medicinally relevant molecules.
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A Two Step Hydrothermal Synthesis Approach to Monodispersed Colloidal Carbon Spheres

A Two Step Hydrothermal Synthesis Approach to Monodispersed Colloidal Carbon Spheres

The synthesis strategy for the synthesis of monodispersed CCS is similar as those for fabricating polymer and/or silica spherical colloids with narrow size distributions [26– 30]. In a typical procedure, the carbon seeds (*93 nm in diameter, Fig. 1f) prepared by one-step approach under the glucose concentration of 0.1 M were divided equally into four parts. Each part was then transferred into an autoclave separately by fixing the total volume at 600 mL, followed by addition of an appropriate amount of glucose with concentrations of 0.1, 0.2, 0.3, and 0.4 M, respectively. The mixture was further heated at 160 °C for 8 h with gentle stirring to insure the reaction homogeneous. After the heating treatment, the reaction system was cooled to room temperature naturally. The precipitates were col- lected by centrifugation and then rinsed with deionized water and alcohol for three times, respectively. Ultrasonic operation was used to re-disperse the precipitates during the rinsing process. Finally, the colloidal carbon spheres were isolated for further characterizations.
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Optimization of A Two-Step Method to Synthesize Azelaic Acid from Oleic Acid

Optimization of A Two-Step Method to Synthesize Azelaic Acid from Oleic Acid

The present study deals with the oxidative cleavage of oleic acid (OA) using hydrogen peroxide and tungstic acid as a catalyst to produce azelaic acid. A two-step method has been expanded for the optimization of a new route of azelaic acid synthesis with the addition of sodium hypochlorite as the co-oxidation. The Central Composite Design (CCD) and Response Surface Methodology (RSM) were performed to optimize the production of azelaic acid. The interaction effect among catalyst concentration, substrate molar ratio and temperature were done for optimization the conversion of oleic acid. Maximum oleic acid conversion of 99.11% was reached at substrate molar ratio of 4/1 (H 2 O 2 /OA), a catalyst concentration of 1.5% (w/wOA) and temperature of 70 o C. The GC analysis
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Basic ionic liquid promoted one step synthesis of 2 alkylsubstituted Chromanones

Basic ionic liquid promoted one step synthesis of 2 alkylsubstituted Chromanones

We studied the representative reaction for preparation of 6a from coupling of orthohydroxy acetophenone (4a) and ethyl propiolate (5) mediated by basic ionic liquid [bmIm]OH to develop the optimal reaction conditions (Scheme 1). Although, literature reveals this reaction in two subsequent steps in which, firstly hydroxyl group of phenol is being protected, followed by cyclization to get a 2-alkyl substituted chromanone derivative (6a) to drive the reaction towards completion. Wherein, we tried to develop the method using [bmIm]OH catalyst to synthesize 2- alkyl substituted chromanone derivative (6a) in a single step. This clearly indicating that [bmIm]OH catalyst is sufficiently effective
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Two-step Synthesis of LiVP2O7/C for Use as Cathode Material in Lithium-Ion Batteries

Two-step Synthesis of LiVP2O7/C for Use as Cathode Material in Lithium-Ion Batteries

The ongoing energy crisis and environmental pollution are arguably two of the greatest challenges faced by society today. To solve these problems, it is imperative to develop novel clean and renewal secondary energy sources. As a recyclable green energy source, lithium-ion batteries are attracting ever-increasing attention and have already found wide applicability [1, 2]. The performance and production cost of the cathode material, which is the primary component of lithium-ion batteries, directly determines their suitability for various applications. Therefore, it is critical to develop suitable cathode materials [3, 4]. At present, the commercial cathode materials of lithium-ion batteries include LiCoO 2 [5, 6], LiMn 2 O 4 [7, 8] , and LiFePO 4 [9, 10]. Based on the properties of LiFePO 4 , other
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A Two-Step Method for the Low-Sidelobe Synthesis of Uniform Amplitude Planar Sparse Arrays

A Two-Step Method for the Low-Sidelobe Synthesis of Uniform Amplitude Planar Sparse Arrays

Inspired by the efficiency of the iterative Fourier transform (IFT) [26–28] in synthesizing both linear and planar thinned arrays (PTAs), a hybrid method based on the IFT and the algorithm of DE, called IFT-DE, was proposed in [29] for the synthesis of a uniformly amplitude linear sparse array (LSA) including many elements. In the first step of the method, the aperture of LSA is divided into a set of half wavelength spaced lattices. Then, a linear thinned array (LTA) with reduced sidelobe level is obtained through performing the IFT, and the filling factor of the LTA is determined by the total number of elements within the LSA. In the second step, for the same thinned array, the elements spaced equal to or greater than a wavelength are selected as the candidates whose locations will be optimized by the DE procedure. Thanks to the high calculation speed of the FFT. The use of IFT helps to efficiently find an LTA with improved sidelobe performance. Therefore, the CPU-time is mainly occupied by the DE. Not only that, due to the specified selection rule, the number of elements needed for optimization is considerably reduced. As a result, the LSA could be synthesized at relative low computational burden. In this paper, the IFT-DE is further extended to the synthesis of a uniform amplitude PSA with apertures ranging from small to moderate size. There are mainly two differences between the method in this paper and the algorithm proposed in [29]. Firstly, the 2D-FFT is performed over 2D lattices to get a planar thinned array (PTA). Secondly, unlike the strategy of DE/rand/1 used in [29] to generate the mutant vectors, the strategy of DE/local-to-best/1 is adopted in this paper.
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Facile two-step Electrodeposition Synthesis of CuO Nanowires for Ultrasensitive Non-Enzymatic Sensing of Glucose

Facile two-step Electrodeposition Synthesis of CuO Nanowires for Ultrasensitive Non-Enzymatic Sensing of Glucose

In this manuscript, well-defined copper(II) oxide nanowires (CuO NWs) structures were successfully synthesized by simple, template- and surfactant-free two-step electrodeposition method. The obtained CuO NWs were investigated using field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the CuO NWs modified glassy carbon (CuO NWs/GC) electrode towards nonenzymatic detection of glucose (Glc) under alkaline conditions were studied by cyclic voltammetry (CV) and chronoamperometry. Excellent electroreduction activity of CuO NWs towards Glc was observed. The CuO NWs/GC sensor was characterized by the wide linear range for Glc (0.0125-4.29 mM), high sensitivity (759.86 μA mM −1 cm −2 ), short response time (4s) and the low limit of detection (LOD = 4.17 μM). Moreover, the sensor showed good reproducibility, anti-interferant ability and long-term stability. Hence it suggests a potential applicability of CuO NWs/GC as a sensor for nonenzymatic detection and quantification of glucose.
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Synthesis of Novel Double Layer Nanostructures of SiC–WOx
              by a Two Step Thermal Evaporation Process

Synthesis of Novel Double Layer Nanostructures of SiC–WOx by a Two Step Thermal Evaporation Process

by Baek et al. [20] by a simple two-step evaporation process and the hierarchical WWOs were found to exhibit promis- ing field emission properties. Tak et al. [34] synthesized heteronanojunction of ZnO nanorods on SiC nanowires by a combination of thermal evaporation and MOCVD process. Bae et al. [25] have fabricated heterostructures of ZnO nanorods with various 1D nanostructures (CNTs, GaN, GaP, and SiC nanowires) by thermal chemical vapor deposition of Zn at a low temperature. Shen et al. [35] have synthesized hierarchical SiC nanoarchitectures by a simple chemical vapor deposition process and reported their field emission properties. Since there are no reports available on the heteronanostructures of WO 3 with SiC up to our
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Synthesis and Characterization of Hydrophobic Silica Aerogel by Two Step(Acid-Base) Sol-Gel Process

Synthesis and Characterization of Hydrophobic Silica Aerogel by Two Step(Acid-Base) Sol-Gel Process

alcosols last for 12 hours. After the sols were set, a small quantity of ethanol was added over the gels in order to prevent the evaporation of pore solvent, the shrinkage and cracking of the gel. The alcogels were aged for 6 h in ethanol at room temperature. Before the surface modification of the gel was carried out, the present ethanol in the alcogels was exchanged with a nonpolar solvent such as hexane in order to avoid the reverse reaction of surface modification, which generally occurs in polar solvents. For this purpose, the alcogels were kept in hexane solvent (50 mL) for 12 h. Then, the surface modification was carried out by immersing the alcogels in a hexane bath containing trimethylchlorosilane (TMCS). The molar ratio of TEOS/TMCS was kept constant at 2. Silica aerogels were obtained by the atmospheric drying of the gels in an oven at 65 °C for 4 h, 80 °C for 2 h and 120 °C for 2 h[24]. In order to obtain fixed weight of silica aerogel, the sample pieces were heated in an oven at 120°C for an hour and then desiccated.
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The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

Due to their diverse biological activities, a variety of synthetic pathways to 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones has been developed over the past two decades [10-22]. The photodecarboxylative addition of phenylacetates to phthal- imides represents a mild alternative entrance to these target molecules [23-31]. The reaction utilizes phenylacetate salts as readily available alkylation agents [32,33]. Selected transfor- mations have been furthermore realized on large multigram scales [25,34,35] and in continuous-flow mode [36-40]. The photodecarboxylation procedure was subsequently applied to the synthesis of 2-dialkylaminoalkyl-3-arylmethylene-2,3- dihydro-1H-isoindolin-1-ones.
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Two-step Synthesis and Characterization of MnCo2O4 Composite and its Electrochemical Performance

Two-step Synthesis and Characterization of MnCo2O4 Composite and its Electrochemical Performance

method, and electrochemical performance testing shows that these materials can be used as electrode materials of a supercapacitor. During preparation, ammonium fluoride plays an important role on the morphology. It was shown that the nanosheet that grows evenly on the base of the nickel foam belongs to nanostructured MnCo 2 O 4 . The electrochemical property testing shows that this composite electrode

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Isothiourea catalyzed enantioselective functionalization of 2 pyrrolyl acetic acid : two step synthesis of stereodefined dihydroindolizinones

Isothiourea catalyzed enantioselective functionalization of 2 pyrrolyl acetic acid : two step synthesis of stereodefined dihydroindolizinones

ABSTRACT: Catalytic enantioselective functionalization of 2-pyrrolyl acetic acid with trichloromethyl enones using isothiourea catalysis is reported, leading to a range of stereodefined diesters and diamides after nucleophilic ring-opening with either methanol or benzylamine (30 examples, up to >95:5 dr and >99:1 er). Subsequent intramolecular Friedel-Crafts reaction allows access to dihydroindolizinones in high yields and stereofidelity (6 examples, up to >95:5 dr and 99:1 er)

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One Pot Two Step Synthesis of 2-Arylidenehydrazinyl-4-arylthiazole

One Pot Two Step Synthesis of 2-Arylidenehydrazinyl-4-arylthiazole

thiazole derivatives is important for their wide range of pharmaceutical and biological properties. Regarding the synthesis of hydrazinyl-thiazoles, general procedure has been reported in the literature. The cyclization of thiosemicarbazones with α-halocarbonyl compounds in alcohol under reflux resulted in hydrazinyl-thiazoles derivatives 14 . Now

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Synthesis of highly substituted 2-spiropiperidines

Synthesis of highly substituted 2-spiropiperidines

With a one-pot procedure developed its scope was explored using several different δ-N-Boc-imines 12 and ketones 10 (Table 3). For the majority of cases (entry 1-4, 6 and 7) the one-pot reaction generated 2-spiropiperidines in moderate to good yields, and in examples 11h, 11i, 11k and 11p these were higher yields than for the two-pot procedure. 2- Spiropiperidines 11t, 11u, 11v, 11w and 11x (entries 6-10) had not been synthesised previously by the two-pot method. In the cases of entries 7 and 8, the diastereomeric ratio of 11u and 11v had to be determined after silica plug filtration due to the overlapping peaks of some impurities.
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A NOVEL STUDIES OF SYNTHESIS OF NANOPARTICAL OF SOME LACTOSYLATED DITHIOBIURETS AND THEIR XRD STUDIES

A NOVEL STUDIES OF SYNTHESIS OF NANOPARTICAL OF SOME LACTOSYLATED DITHIOBIURETS AND THEIR XRD STUDIES

Carbohydrates derivatives have been extensively investigated including synthesis, characterization and biological activity. Partly due to the facts that many natural occurring saccharides and synthesized analogues exhibit various and potent biological activities and they have been widely employed as agrochemicals and pharmaceuticals 4-7 .

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Towards Computer-Vision-Based Learning from Demonstration (CVLfD): Chess Piece Recognition

Towards Computer-Vision-Based Learning from Demonstration (CVLfD): Chess Piece Recognition

Abstract: We present an approach to develop algorithms to offer ‘Learning from Demonstration’. Our aim is to realize Computer Vision as resource-efficient as possible in applications where people interact with computers or -as a special case- with robots. This paper explains the development of a classification program which is to be integrated to a robot that will autonomously play chess. The problem is to perform a classification on a 12 class data set of chess pieces which works on a real-time video feed. We develop two different approaches to solve the problem: A one-step classification is compared to a two-step procedure based on accuracy, computational time and robustness.
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Structure, Properties and Medical Advances for Biocellulose Applications: A Review

Structure, Properties and Medical Advances for Biocellulose Applications: A Review

BC structures are formed by extracellulary-excreted nanofibers (about 20-100nm in diameter and around 100µm in length) and has a very high surface area per unit mass, produced by various species of bacteria, including Acetobacter, Rhizobium, Agrobacterium and Sarcina. The ribbons are made up of bundles of cellulose microfibrils of 2-4nm in diameter (figure 3). The average mesh size (distance between junction points) is 0.523±0.273µm, while the orientation (the average angle formed by the segments and the x-axis) of the nanofibers is 85.64±0.56° [12-15]. One of the greatest advantages of microbial cellulose is its ability to be molded into almost any size and shape during its synthesis without causing any significant alteration of its physical properties. BC shows high tensile strength and modulus, due to high crystalline structure and reduced fiber diameter. For instance, the BC microfibrils have a density of 1600kg/m 3 , Young's modulus of 138GPa and tensile strength of at least 2GPa, which are almost equal to those of aramid fibers [14,
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A Classifier for Schema Types Generated by Web Data Extraction Systems

A Classifier for Schema Types Generated by Web Data Extraction Systems

Fig. 7: The proposed set-type filtration algorithm. As shown in Figure 7, for a web site, given as input to the set- type filtration algorithm the site schema as a tree (ST), a set of web pages from the site (Σ), and the pattern tree (constructed by FiVaTech), the algorithm traverses the schema tree ST in a post-order traversing fashion (lines 1-2). For each set-type node c (line 4), we use the instances of c from the collection of pages Σ to handle it by calling (in order) the two methods “handleIncorrectType” and “handleIncompleteType”. The first method handleIncorrectType shown in Figure 8, if c is an incorrect set type, divides the instances of the type c into different clusters (lines 4-13) such that all instances in each cluster are similar (peer instances) while two instances of different clusters are not similar. The method works as follows. Let 𝐷 = 𝐼𝑛𝑠𝑡𝑎𝑛𝑐𝑒 𝑐 = 𝑥 1 , 𝑥 2 , … , 𝑥 𝑘 is a set of all
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QSAR analysis and validation studies on substituted
spiropiperidines as GlyT1 inhibitors

QSAR analysis and validation studies on substituted spiropiperidines as GlyT1 inhibitors

The model was further validated by applying the y-randomization test. As the model selection included F-stepping, several random shuffles of the dependent as well as independent variables were performed and the results are shown in Table VI. The low R 2 and Q 2 values indicate that the results obtained in our original model (Eq. 7) are not due to chance correlation. Alternatively, Table VII given below represents the leverage values of training and validation sets. RMSE of training and validation sets were calculated based on Euclidean distance method using Ambit software and the values are within the limits, RMSE for training set is 0.37 and RMSE for validation set is 0.04, respectively.
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