93 research outputs found
Copper-Catalyzed Simultaneous Activation of C–H and N–H Bonds: Three-Component One-Pot Cascade Synthesis of Multisubstituted Imidazoles
No full textA copper-catalyzed expedient, practical, and straightforward approach for the one-pot three-component modular synthesis of multisubstituted imidazoles has been described by using arylacetic acids, N-arylbenzamidines, and nitroalkanes. The reaction involves simultaneous activation of C–H and N–H bonds of arylacetic acids and N-arylbenzamidines, respectively. The use of inexpensive copper sulfate as a catalyst, readily available starting materials, and Celite-free workup makes this protocol economically viable. Multisubstituted imidazoles were obtained in moderate to good yields with significant functional group tolerance and high regioselectivity
An Efficient Synthesis of 1,2,4-Trisubstituted Imidazoles from Arylacetic Acids and N -Arylbenzamidines via Simultaneous C-H and N-H Bond Activation
No full textA convenient and effective FeCl3 catalyzed one-pot three
component protocol for the synthesis of 1,2,4-trisubstituted
imidazoles from arylacetic acids, N-arylbenzamidines and nitromethane
via simultaneous CH and NH bond activation has
been developed. The reaction involves CH activation of
arylacetic acid to form aromatic aldehyde which on condensation
with N-arylbenzamidine gives azadiene. Nitromethane on
Michael addition with azadiene produces ring annulated
intermediate which upon subsequent cyclization-elimination
sequence offers imidazole. The process utilizes readily available
arylacetic acids and inexpensive catalyst. This user friendly
protocol provided 1,2,4-trisubstituted imidazoles in moderate
to good yields with high functional group tolerance and ample
substrate scope
Tandem Protocol for the Synthesis of 3-Acyl Benzothiadiazine 1,1-Dioxides
No full textA metal-free and efficient tandem synthesis of 3-acyl 3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxides and 3-acyl-2H-1,2,4-benzothiadiazine-1,1-dioxides has been developed via C−H functionalization of ethynylarenes and ethenylarenes followed by condensation with 2-aminobenzenesulfonamide. The reaction involves the formation of arylglyoxal as an intermediate from multiform substrates through Kornblum oxidation in the presence of iodine and DMSO. Use of simple and readily available starting materials, inexpensive reagent, broad substrate scope and a very simple operation are noteworthy features of this protocol. This method provides an easy access to pharmaceutically important 3-acyl-1,2,4-benzothiadiazine-1,1-dioxides in good yields
Conditional models for 3D human pose estimation:
No full textHuman 3d pose estimation from monocular sequence is a challenging problem, owing to highly articulated structure of human body, varied anthropometry, self occlusion, depth ambiguities and large variability in the appearance and background in which humans may appear. Conventional vision based approaches to human 3d pose estimation mostly employed "top-down methods", which used a complete 3d human model, in a hypothesized pose, to explain the configuration of the humans in the observed 2d image. In this thesis, we work with "bottom-up methods" for human pose estimation, that use low level image features to directly predict 3d pose. The research draws on recent innovations in statistical learning, observation-driven modeling, stable image encodings, semi-supervised learning and learning perceptual representations. We address the problems of (a) modeling pose ambiguities due to 3d-to-2d projection and self occlusion, (b) lack of sufficient labeled data for training discriminative models and (c) high dimensionality of human 3d pose state space. In order to resolve 3d pose ambiguities, we use multi-valued functions to predict multiple plausible 3d poses for an image observation. We incorporate unlabeled data in a semi-supervised learning framework to constrain and improve the training of discriminative models. We also propose generic probabilistic Spectral Latent Variable Models to efficiently learn low dimensional representations of high dimensional observation data and apply it to the problem of human 3d pose inference.Ph.D.Includes bibliographical references (p. 182-193)by Atul Kanauji
ChemInform Abstract: Direct Allylation of Alcohols Using Allyltrimethylsilane and a Move Towards an Economical and Ecological Protocol for C—C Bond Formation
No full textComputational Investigation of Microreactor Configurations for Hydrogen Production from Formic Acid Decomposition Using a Pd/C Catalyst
No full textThe need to replace fossil fuels with sustainable alternatives has been a critical issue in recent years. Hydrogen fuel is a promising alternative to fossil fuels because of its wide availability and high energy density. For the very first time, novel microreactor configurations for the formic acid decomposition have been studied using computational modeling methodologies. The decomposition of formic acid using a commercial 5 wt % Pd/C catalyst, under mild conditions, has been assessed in packed bed, coated wall, and membrane microreactors. Computational fluid dynamics (CFD) was utilized to develop the comprehensive heterogeneous microreactor models. The CFD modeling study begins with the development of a packed bed microreactor to validate the experimental work, subsequently followed by the theoretical development of novel microreactor configurations to perform further studies. Previous work using CFD modeling had predicted that the deactivation of the Pd/C catalyst was due to the production of the poisoning species CO during the reaction. The novel membrane microreactor facilitates the continuous removal of CO during the reaction, therefore prolonging the lifetime of the catalyst and enhancing the formic acid conversion by approximately 40% when compared to the other microreactor configurations. For all microreactors studied, the formic acid conversion increases as the temperature increases, and the liquid flow rate decreases. Further studies revealed that all microreactor configurations had negligible internal and external pore diffusion resistances. The detailed models developed in this work have provided an interesting insight into the intensification of the formic acid decomposition reaction over a Pd/C catalyst
Synthesis and antibacterial activity of new oxadiazolo[1,3,5]-triazine, 1,2,4 triazolo and thiadiazolo 1,3,4 oxadiazole derivatives
No full text1710-17153-Formyl-4-hydroxycoumarin has been treated with semicarbazide to give 4-hydroxy-2-oxo-2H[1]-benzopyran-3-aldehyde semicarbazone 1a-d, which on oxidative cyclization with bromine in glacial acetic acid in the presence of anhydrous sodium acetate gives 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 2a-d. 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one on reaction with benzaldehyde gives 4-hydroxy-3-(5-benzylidine imino 1,3,4-oxadiazol-2-yl)-2H[1]-benzopyran-2-one 3a-d. 3a-d on (4+2) cycloaddition with phenyl isothiocynate gives 3-(6,7-diphenyl-5-thioxo-6,7-dihydro-5H-[1,3,4]oxadiazolo[3,2-][1,3,5]triazin-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 4a-d. 2a-d undergoes regioselective condensation with KSCN in methanol to give N-[5-(4-hydroxy-2-oxo-2H[1]-benzopyran-3-yl)-1,3,4,-oxadiazol-2-yl]thiourea 5a-d whereas with phenyl isothiocynate it gives N-[5-(-4-hydroxy-2-oxo-2H[1]benzopyran-3-yl)-1,3,4-oxadiazole-2-yl]-N'-phenylthiourea 7a-d. 5a-d reacts with thionyl chloride in pyridine to give 4-hydroxy-3-(6-thioxo-5,6-dihydro[1,2,4]triazolo[5,1-b][1,3,4]oxadiazol-2-yl)-2H[1]-benzopyran-2-one 6a-d. 7a-d on treatment with ethanol and iodine yields 4-hydroxy-3-[6-phenylimino-6H-[1,2,4]-thiadiazolo[3,2-b][1,3,4]-oxadiazol-2-yl]-2H[1]benzopyran-2-one 8a-d
, and sp C—H Functionalization and Oxidative Cross Coupling with Benzamidines Hydrochloride: A Promising Approach for the Synthesis of α‐Ketoimides.
No full text
A novel twisted Donor-Acceptor structures with cyano substituents for advancements in Near-Infrared Red TADF Emitters
No full textThe designing and development of near-infrared (NIR) red emitters have attracted significant attention owing to the challenges of achieving the necessary energy levels for harvesting both singlet and triplet excitons and their unique requirements for this spectral range. Herein, we have reported the designing and synthesis of two novel red TADF emitters 4,4\u27-(3,6-bis(9,9-dimethylacridin-10(9H)-yl)dibenzo[a,c]phenazine-11,12-diyl)dibenzonitrile (Ac-PhCNDBPZ) and 4,4\u27-(3,6-di(10H-phenoxazin-10-yl)dibenzo[a,c]phenazine-11,12-diyl)dibenzonitrile (PXZ-PhCNDBPZ) having twisted donor-acceptor structures. A cyano substituent helps to increase the wavelength towards the redshift. These emitters show near-IR emissions at 602 and 698 nm. This work proves that the cyano substituent and rigid acceptor with a strong donor could be an effective approach to exploring high-efficiency red near-infrared TADF materials
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