Kaushik Chakrabarti
@szymczakgroup.com
Postdoctoral researcher, Department of Chemistry
University of Michigan
RESEARCH, TEACHING, or OTHER INTERESTS
Chemistry, Inorganic Chemistry, Organic Chemistry, Catalysis
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Kaushik Chakrabarti, Alice Spangenberg, Vasudevan Subramaniyan, Andreas Hederstedt, Omar Y. Abdelaziz, Alexey V. Polukeev, Reine Wallenberg, Christian P. Hulteberg, and Ola F. Wendt
Royal Society of Chemistry (RSC)
Finding alternative and sustainable ways to produce, store and convert energy is key for reducing fossil fuel-based CO2 emissions.
Kaushik Chakrabarti, Michael M. Wade Wolfe, Shuo Guo, Joseph W. Tucker, Jisun Lee, and Nathaniel K. Szymczak
Royal Society of Chemistry (RSC)
We report a metal-free strategy to access fluoroalkyl–olefin linkages from RCF2H (R = aryl, H, F and fluoroalkyl) precursors and vinyl-pinacol boronic ester (BPin) reagents.
Abdelrazek H. Mousa, Kaushik Chakrabarti, Ghodsieh Isapour, Jesper Bendix, and Ola F. Wendt
Wiley
New PCNPy pincer nickel complexes have been synthesized through a short synthetic route. Incorporating pyridine as the nitrogen side arm facilitated the C–H activation in the PCN ligand and allowed the cyclometallation with nickel to take place at room temperature. Pyridine also enhanced the stability of β‐hydrogen‐containing alkyl complexes. Also, the symmetric NCN nickel complex with pyridine side arms was successfully obtained giving a rare example of such type of complexes to be prepared through direct C–H activation. Furthermore, preliminary results showed that the (PCNPy)Ni–Br is active in Kumada coupling reactions particularly the coupling of aryl halides with aryl Grignard reagents.
Kaushik Chakrabarti, Kuheli Dutta, and Sabuj Kundu
Royal Society of Chemistry (RSC)
The Ru(ii) complex catalysed direct transformation of acyl azides intoN-methylamines was developed for the first time using methanolviathe one-pot Curtius rearrangement and borrowing hydrogen methodology.
Bhaskar Paul, Milan Maji, Kaushik Chakrabarti, and Sabuj Kundu
Royal Society of Chemistry (RSC)
In this review, the progress of tandem transformation of nitro, nitrile and azide functionalities is summarised to develop new C–C and C–N bonds as well as multi-component reactions using alcohols.
Milan Maji, Kaushik Chakrabarti, Dibyajyoti Panja, and Sabuj Kundu
Elsevier BV
Kaushik Chakrabarti, Milan Maji, and Sabuj Kundu
Royal Society of Chemistry (RSC)
A sustainable protocol for the synthesis of various pharmaceutically relevant N-heterocyclic moieties was developed in water. A metal–ligand cooperative mechanism was proposed for this system based on kinetic and DFT studies.
Bhaskar Paul, Sujan Shee, Dibyajyoti Panja, Kaushik Chakrabarti, and Sabuj Kundu
American Chemical Society (ACS)
Direct and selective synthesis of N,N-dimethylated amines from nitriles using methanol as C1 building blocks is reported using an air- and moisture-stable ruthenium complex. Following this process, various aromatic as well as aliphatic nitriles were converted to the corresponding N-methylated amines. Interestingly, tandem C-methylation as well as N-methylation was achieved by introducing multiple methyl groups. The practical aspect of this process was revealed by preparative-scale reactions with different nitriles and the synthesis of anti-allergic drug “avil”. Several kinetic experiments and detailed DFT calculations were carried out to understand the mechanism of this process.
Bivas Chandra Roy, Subhankar Debnath, Kaushik Chakrabarti, Bhaskar Paul, Milan Maji, and Sabuj Kundu
Royal Society of Chemistry (RSC)
The catalytic activity of Ru(ii) complexes in sustainable C–C and C–N bond formation is enhanced by using a functionalized 2,2′-bipyridine ligand.
Milan Maji, Kaushik Chakrabarti, Bhaskar Paul, Bivas Chandra Roy, and Sabuj Kundu
Wiley
AbstractAn air and moisture stable 2‐hydroxypyridine based bifunctional ruthenium NNN‐pincer complex catalyzed efficient (TON=42840) N‐alkylation of amines under mild conditions. Surprisingly, with cyclic secondary amines this methodology selectively produced only amides. Notably, N‐methylation of several amines was achieved by using methanol as a green methylating agent. Furthermore, with lower catalyst loading (0.2 mol%) and shorter reaction time (6 h) numerous substituted quinolines were synthesized from 2‐aminobenzyl alcohols and secondary alcohols. The effectiveness of this protocol was further extended by successfully synthesizing 2‐alkylaminoquinolines in a one‐pot fashion from amino alcohol, aliphatic nitriles, and alcohols. Gram scale synthesis of various compounds was also investigated to demonstrate the synthetic applicability of this methodology.magnified image
Kaushik Chakrabarti, Anju Mishra, Dibyajyoti Panja, Bhaskar Paul, and Sabuj Kundu
Royal Society of Chemistry (RSC)
The selective synthesis of various N,N-dimethylated and N-monomethylated amines from organic azides using methanol as a methylating agent is reported.
Sujan Shee, Bhaskar Paul, Dibyajyoti Panja, Bivas Chandra Roy, Kaushik Chakrabarti, Kasturi Ganguli, Ayan Das, Gourab Kanti Das, and Sabuj Kundu
Wiley
AbstractA Ru(II) NHC complex (loading down to 0.001 mol%) catalyzed cross coupling of a broad range of aromatic, aliphatic and heterocyclic alcohols is reported. This protocol also functioned efficiently under solvent‐free conditions. Remarkably, this catalytic system disclosed so far the highest TON of 288000 for the cross coupling of alcohols. Notably, this methodology was successfully applied for the one‐pot synthesis of a range of flavan derivatives. A detailed DFT studies and kinetic experiments were performed to understand the reaction mechanism as well as the high reactivity of this catalytic system.magnified image
Kaushik Chakrabarti, Milan Maji, Dibyajyoti Panja, Bhaskar Paul, Sujan Shee, Gourab Kanti Das, and Sabuj Kundu
American Chemical Society (ACS)
Ru(II) catalyzed tandem synthesis of α-branched methylated ketones via multicomponent reactions following the hydrogen borrowing process is described. This nonphosphine-based air and moisture stable catalyst efficiently produced various methylated ketones using methanol as a methylating agent. This system was found to be highly effective in three-component coupling between methanol, primary alcohols, and methyl ketones. A proposed catalytic cycle for the α-methylation is supported by DFT calculations as well as kinetic experiments.
Bhaskar Paul, Sujan Shee, Kaushik Chakrabarti, and Sabuj Kundu
Wiley
AbstractA simple air‐ and moisture‐stable, highly efficient ruthenium NNN pincer complex is reported for the first time to catalyze the tandem transformation of various aromatic and aliphatic nitro compounds into the corresponding N‐methylated amines in up to 98 % yield by using methanol as a green methylating agent. Gram‐scale reactions of challenging nitro substrates demonstrated the practical application aspects of this catalytic system. Importantly, the N‐methylamine moiety could be smoothly introduced to various complex molecular structures without using any expensive palladium/phosphine/amine‐based cross‐coupling reactions.
Bivas Chandra Roy, Kaushik Chakrabarti, Sujan Shee, Subhadeep Paul, and Sabuj Kundu
Wiley
AbstractCatalytic activities of a series of functional bipyridine‐based RuII complexes in β‐alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional RuII complex (3 a) bearing 6,6’‐dihydroxy‐2,2’‐bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon−carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β‐alkylated secondary alcohols this protocol is a rare one‐pot strategy using a metal–ligand cooperative RuII system. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction.
Kaushik Chakrabarti, Bhaskar Paul, Milan Maji, Bivas Chandra Roy, Sujan Shee, and Sabuj Kundu
Royal Society of Chemistry (RSC)
Bifunctional Ru(ii) complex (0.1 mol%) catalysed one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol were carried out successfully following the atom economical borrowing hydrogen methodology.
Bhaskar Paul, Kaushik Chakrabarti, Sujan Shee, Milan Maji, Anju Mishra, and Sabuj Kundu
Royal Society of Chemistry (RSC)
A convenient and highly efficient in situ generated Ru(ii) system for synthesizing functionalized amines and mechanistic studies and comparison with iridium systems is presented.
Bhaskar Paul, Kaushik Chakrabarti, and Sabuj Kundu
Royal Society of Chemistry (RSC)
A rare example of a highly active bifunctional Ru(ii) catalyst containing only one 2-hydroxypyridine (2-HP) unit is presented which exhibited exceptionally high catalytic activity in transfer hydrogenation of ketones and nitriles.