Amrita Das
@m.christuniversity.in
Assistant Professor, CHRIST (Deemed to be University)
CHRIST (Deemed to be University)
RESEARCH, TEACHING, or OTHER INTERESTS
Organic Chemistry, Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Haruro Ishitani, Tomoya Kawase, Amrita Das, and Shū Kobayashi
Royal Society of Chemistry (RSC)
Selective hydrodechlorination under continuous-flow conditions for a fungicide intermediate was investigated using heterogeneous Pd catalysts, and the desired difluoromethyl-substituted pyrazole obtained quantitatively at 1.5 h−1 of SVmol value.
Amrita Das and Tarun K. Panda
Wiley
AbstractThis review discusses the immense progress made over recent years in metal‐free catalytic hydroboration. Reactions with several unsaturated functional groups, such as alkynes, alkenes, carbonyl compounds, carbon dioxide, carbodiimides, imines, allenes, pyridines, carboxylic acid derivatives etc., have been explored. Although there are significant developments in hydroboration reactions using metal‐based catalysts, metal‐free catalytic strategies are more desirable from a sustainability perspective. Considerable effort has been made by various research groups on metal‐free catalysts in the hydroboration of unsaturated compounds. Lewis acid, Brønsted acid, Lewis acid‐base pairs, and frustrated Lewis pairs were involved as metal‐free sources to catalyze hydroboration reactions in a sustainable manner. Detailed mechanisms of the catalytic pathways of metal‐free hydroboration are also discussed in this review. This discussion will provide an overview of the extent of work carried out as well as indicate scope for future research.
Amrita Das, Supriya Rej, and Tarun K. Panda
Royal Society of Chemistry (RSC)
Development of efficient Al-complexes and their crucial roles in catalytic selective hydroboration of several unsaturated compounds such as carbonyls, alkenes, alkynes, imines, nitriles and others were well documented in this review.
Amrita Das and Naoto Chatani
Royal Society of Chemistry (RSC)
The Rh(i)-catalysed imine-directed oxidative [3 + 2] cycloaddition of benzylamines with maleimides is reported. The reaction is proposed to proceed via a zwitterionic intermediate.
Supriya Rej, Amrita Das, and Tarun K. Panda
Wiley
AbstractHydroboration of alkynes is of special interest to researchers since it is the most straightforward process for the synthesis of highly important vinylborane synthetic intermediate compounds. It is significant in terms of both regioselectivity and stereoselectivity, since several positional isomers are formed during the process of hydroboration. Given the importance of this class of compounds, an extensive study has been carried out regarding catalytic condition development and detailed mechanistic studies for selectively obtaining a single isomer. This review comprehensively summarizes both the regioselective and stereoselective catalytic hydroboration of alkynes. It is aimed at giving readers accurate knowledge of the catalytic systems available for the hydroboration of certain alkynes. We anticipate that this inclusive review will encourage researchers to explore more new types of catalytic systems to achieve the remarkable process of hydroboration of alkynes.magnified image
Amrita Das and Naoto Chatani
American Chemical Society (ACS)
Supriya Rej, Amrita Das, and Naoto Chatani
Royal Society of Chemistry (RSC)
We present the metal-free ortho-C–H borylation of 2-pyrimidylanilines to afford synthetically important boronic esters and tetra-coordinated triarylboranes, which could be useful in materials science as well as Lewis-acid catalysts.
Nozomi Ohara, Amrita Das, Sanjit K. Mahato, and Naoto Chatani
The Chemical Society of Japan
A continuous-flow synthesis of α-amino acid derivatives via a nitrene transfer by the Ir(III)-catalyzed α-C-H amidation of 2-acylimidazoles with dioxazolones is reported.
Amrita Das and Naoto Chatani
American Chemical Society (ACS)
The Rh-catalyzed C-H alkylation of benzylamine derivatives with unactivated 1-alkenes that proceeds via a picolinamide directing group is reported. The crucial role of an acid additive in this transformation is confirmed. Aromatic acids showed high linear selectivity, and aliphatic acids provided branched alkylation products as the major product. The reaction has a broad scope for benzylamines and alkenes. Deuterium labeling experiments suggest that a Rh-carbene intermediate is involved in the case of linear product formation. A different reaction pathway, however, appears to be involved in the case of branched alkylation products, and this pathway also appeared to be a minor pathway in linear-selective reactions.
Supriya Rej, Amrita Das, and Naoto Chatani
Elsevier BV
Amrita Das and Naoto Chatani
Royal Society of Chemistry (RSC)
Rh(i)- and Rh(ii)-catalyzed C–H alkylation of benzylamines with alkenes using a picolinamide derivative as a directing group is reported under both batch and flow.
Amrita Das, Haruro Ishitani, and Shū Kobayashi
Wiley
AbstractA two‐step continuous‐flow synthesis of substituted pyrazole derivatives has been developed via the formation of vinylidene keto esters as key intermediates. Heterogeneous Ni2+‐montmorillonite was found to be an efficient catalyst for orthoester condensation of 1,3‐dicarbonyls under flow conditions. The intermediate reacted with methylhydrazine to afford pyrazole derivatives, for which suitable selection of a solvent played a key role in achieving high yields and excellent regioselectivities of the desired products. An application of this protocol has been demonstrated by the synthesis of a key intermediate for biologically active pyrazoles such as Bixafen.magnified image
Amrita Das, Kenji Watanabe, Hiroyuki Morimoto, and Takashi Ohshima
American Chemical Society (ACS)
Boronic acid was used to accelerate a three-component reaction of indoles, thiols, and glyoxylic acids for the synthesis of α-sulfanyl-substituted indole-3-acetic acids. Boronic acid catalysis to activate the α-hydroxy group in α-hydroxycarboxylic acid intermediates and intramolecular assistance by free carboxylic acid were the keys to accelerating the product formation.
Amrita Das, Alavala Gopi Krishna Reddy, Jonnada Krishna, and Gedu Satyanarayana
Royal Society of Chemistry (RSC)
A superacid promoted one-pot method was developed for the efficient synthesis of indanones. This process enabled the formation of a dual C–C bond between the aryl isopropyl ketones and benzaldehydes. Interestingly, when the reaction was performed between acetophenones and benzaldehydes, it was impeded after the aldol condensation and resulted in the corresponding chalcones.
Remya Narayanan, Amrita Das, Melepurath Deepa, and Avanish Kumar Srivastava
Wiley
AbstractA new design for a quasi‐solid‐state Forster resonance energy transfer (FRET) enabled solar cell with unattached Lucifer yellow (LY) dye molecules as donors and CdS/CdSe quantum dots (QDs) tethered to titania (TiO2) as acceptors is presented. The Forster radius is experimentally determined to be 5.29 nm. Sequential energy transfer from the LY dye to the QDs and electron transfer from the QDs to TiO2 is followed by fluorescence quenching and electron lifetime studies. Cells with a donor–acceptor architecture (TiO2/CdS/CdSe/ZnS‐LY/S2−‐multi‐walled carbon nanotubes) show a maximum incident photon‐to‐current conversion efficiency of 53 % at 530 nm. This is the highest efficiency among Ru‐dye free FRET‐enabled quantum dot solar cells (QDSCs), and is much higher than the donor or acceptor‐only cells. The FRET‐enhanced solar cell performance over the majority of the visible spectrum paves the way to harnessing the untapped potential of the LY dye as an energy relay fluorophore for the entire gamut of dye sensitized, organic, or hybrid solar cells.