Browsing by Author "Thakur, A"

Now showing 1 - 3 of 3

Cyclocondensation reactions of an electron deactivated 2-aminophenyl tethered imidazole with mono/1, 2-biselectrophiles: synthesis and DFT studies on the rationalisation of imidazo [1, 2-a] quinoxaline versus benzo [f] imidazo [1, 5-a][1, 3, 5] triazepine selectivity switches.
(Royal Society of Chemistry, 2018) Joshi, G.; Chauhan, M; Kumar, R; Thakur, A; Sharma, S; Singh, R.; Wani, A.A.; Sharon, A.; Bharatam, P.V; Kumar, R.
Microwave-promoted ring-closure reactions of 5-amino-1-(2-aminophenyl)-1H-imidazole-4-carbonitrile (7) with various mono/1,2-biselectrophiles are presented. The reaction of 7 with aldehydes, ketones and isocyanates produced the corresponding Pictet–Spengler (PS) products i.e. the imidazo[1,2-a]quinoxaline ring system via 6-endo-trig cyclisation. On the other hand, the reaction of 7 with CH(OEt)3, and CDI resulted in the formation of benzo[f]imidazo[1,5-a][1,3,5]triazepine scaffolds via a 7-exo-trig cyclisation process. The mechanistic aspects of these ring cyclisation processes have been analysed and studied to rationalise 6- versus 7-membered ring formation using density functional theory (DFT). DFT calculations revealed the involvement of N-Heterocyclic Carbene (NHC) in the PS reaction mechanism.
Stability and electronic structure of tricycle-type allotropes of pnictogen monolayers
(American Institute of Physics, 2019) Jamdagni, P; Thakur, A; Kumar ,Ashok; Ahluwalia, P.K.
We report stability and electronic structure of tricycle-type allotrope of pnictogen monolayers within state-of-the-art density functional theory (DFT) calculations. The considered monolayer structure of two-dimensional (2D) As and Sb are found to be energetically more stable than the previously reported puckered and buckled structures, however, 2D Bi prefer zigzag-type high-buckled structure. Electronic band structure calculations suggest the considered monolayers structure to be narrow direct bandgap semiconductors with bandgap ranging 0.2-0.6 eV along with Dirac-cone features at band edges. Spin-orbit coupling (SOC) further reduce the bandgap by shifting the band edges towards Fermi level. We believe that our theoretical study will add more 2D materials with Dirac-cone features in the fascinating class of family and may guide the experimentalists to realize them for various nanoelectronic applications. © 2019 Author(s).
Targeting cancer stem cells pathways for the effective treatment of cancer
(Bentham Science Publishers, 2020) Dwivedi, A.R; Thakur, A; Kumar, V; Skvortsova, I; Kumar, V.
Resistance to chemotherapy and relapse are major hurdles for the effective treatment of cancer. Major reason for this is a small sub population of cancer stem cells (CSCs) and its microenvironment. CSCs are critical driving force for several types of cancer, such as gastric, colon, breast and many more. Hence, for the complete eradication of cancer, it is necessary to develop therapeutic approaches that can specifically target CSCs. Chemical agents that target different proteins involved in CSC signaling pathways, either as single agent or simultaneously targeting two or more proteins have generated promising pre-clinical and clinical results. In the current review article, we have discussed various targets and cellular pathways that can be explored for the effective and complete eradication of CSCs. Some latest developments in the field of design, synthesis and screening of ligands to target cancer stem cells have been summarized in the current review article. � 2020 Bentham Science Publishers.