252 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
Bipolar Host Materials: A Chemical Approach for Highly Efficient Electrophosphorescent Devices
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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
Mutual information relevance networks : functional genomic networks built from pair-wise entropy measurements
No full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis (S.M.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2002.Includes bibliographical references (leaves 27-28).by Atul Janardhan Butte.Thesis (S.M.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2002
Carbazole-benzimidazole hybrid bipolar host materials for highly efficient green and blue phosphorescent OLEDs
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