@article {45518, title = {Gold-catalyzed 1,2-oxyalkynylation of N-Allenamides with ethylnylbenziodoxolones}, journal = {Organic Letters}, volume = {21}, year = {2019}, month = {JAN}, pages = {180-184}, type = {Article}, abstract = {

A gold-catalyzed 1,2-oxyalkynylation of N-allenamides with ethylnylbenziodoxolones (EBXs) has been achieved for the first time. The reaction, which follows a redox-neutral Au(I)/Au(III) catalytic pathway, was enabled in an attempt to exhaust the EBX reagents atom-economically by putting the nucleophilic carboxylate part of EBXs to appropriate use. This constitutes the first example for gold-catalyzed beta-alkynylation of N-allenamides to construct highly valuable 1,3-enynes. The potential of the sequence is further documented by some follow-up transformations.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.8b03651}, author = {Banerjee, Somsuvra and Senthilkumar, Beeran and Patil, Nitin T.} } @article {46796, title = {Anthrone-spirolactam and quinoline hybrid based sensor for selective fluorescent detection of Fe(3+)ions}, volume = {34}, year = {2020}, month = {OCT}, pages = {e5867}, type = {Article}, abstract = {

The synthesis of a novel, and highly selective Fe(3+)ion sensor based on anthrone-spirolactam and its quinoline hybrid ligand is reported. The designed ligand displayed selective detection of Fe(3+)ions with enhanced fluorescence emission. The complexation of Fe(3+)ion led to a red shift of 32 nm from 420 nm to 452 nm, and a several fold increase in intensity with fluorescent green emission. The complexation (detection) of Fe(3+)ions with ligand resulted in chelation enhanced fluorescence and intramolecular charge transfer through the inhibition of C=N isomerization. This hybrid sensor shows high sensitivity and selectivity, spontaneous response, and works on a wide pH range a minimum detection limit of 6.83 x 10(-8)M. Importantly, the sensor works through the fluorescence turn-on mechanism that overcomes the paramagnetic effect of Fe(3+)ions. The binding mechanism between the ligand and the Fe(3+)ions was established from the Job{\textquoteright}s plot method, optical studies, Fourier transfor infrared spectroscopy, NMR titration, fluorescence life-time studies, and density functional theory optimization. The sensor displayed excellent results in the quantification of Fe(3+)ions from real water samples. Furthermore, due to its biocompatibility nature, fluorescent spotting of Fe(3+)ions in live cells revealed its bioimaging applications.

}, keywords = {anthrone-spirolactam-quinoline, Cell imaging, fluorescence, intramolecular charge transfer, iron}, issn = {0268-2605}, doi = {10.1002/aoc.5867, Early Access Date = JUL 2020}, author = {Darole, Ratanamala S. and Christopher Leslee, Denzil Britto and Mukherjee, Anagh and Gonnade, Rajesh G. and Karuppannan, Sekar and Senthilkumar, Beeran} } @article {46819, title = {Gold-catalyzed alkynylative meyer-schuster rearrangement}, journal = {Organic Letters}, volume = {22}, year = {2020}, month = {JUN}, pages = {4792-4796}, type = {Article}, abstract = {

By applying the {\textquoteleft}{\textquoteleft}interplay{\textquoteright}{\textquoteright} mode, which consolidates two key reactivity modes of gold catalysis, namely pi-activation mode and cross-coupling mode, the first alkynylative Meyer-Schuster rearrangement is designed and successfully implemented. The current protocol gives straightforward access to enynones, a highly valuable building block, from easily available propargyl alcohol feedstocks. Control experiments suggest an Au(III) catalyst triggers the Meyer-Schuster rearrangement, whereas monitoring the reaction with ESI-HRMS provided strong evidence in favor of a key alkynylgold(III) intermediate which supports the proposed {\textquoteleft}{\textquoteleft}interplay{\textquoteright}{\textquoteright} scenario.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.0c01596}, author = {Banerjee, Somsuvra and Ambegave, Shivhar B. and Mule, Ravindra D. and Senthilkumar, Beeran and Patil, Nitin T.} } @article {47001, title = {Influence of the ion size on the stability of the smectic phase of ionic liquid crystals}, journal = {Soft Matter}, volume = {16}, year = {2020}, month = {JAN}, pages = {411-420}, type = {Article}, abstract = {

The thermotropic phase behavior of ionic liquids and ionic liquid crystals based on novel N-alkyl-3-methylpyridinium halides, trihalides and dichloroiodates was experimentally studied by polarized optical spectroscopy (POM) and differential scanning calorimetry (DSC) as well as by molecular dynamics (MD) simulation. In the experiments, the existence and thermal range of stability of the smectic phase of these ionic liquid crystals are found to strongly depend on the volume ratio between the cation and anion, that is their relative size. Only compounds with a relatively large volume ratio of the cation to anion, i.e., those with longer cationic alkyl chains and monoatomic halide anions, have a stable smectic A phase. Both melting points and clearing points increase with such a ratio. The MD simulation results qualitatively agree very well with the experimental data and provide molecular details which can explain the experimentally observed phenomena: the stronger van der Waals interactions from the longer alkyl chains and the stronger electrostatic interactions from the smaller anions with a higher charge density increase the stability of both the crystal phase and the smectic phase; this also prevents the ionic layers from easily mixing with the hydrophobic regions, a mechanism that ultimately leads to a nanosegregated isotropic liquid phase.

}, issn = {1744-683X}, doi = {10.1039/c9sm02115a}, author = {Cao, Wudi and Senthilkumar, Beeran and Causin, Valerio and Swamy, Vincent P. and Wang, Yanting and Saielli, Giacomo} } @article {46811, title = {Triethyl phosphite/benzoyl peroxide mediated reductive dealkylation of O-benzoylhydroxylamines: a cascade synthesis of secondary amides}, journal = {European Journal of Organic Chemistry}, volume = {2020}, year = {2020}, month = {JUL}, pages = {4235-4238}, type = {Article}, abstract = {

A new triethyl phosphite/benzoyl peroxide (BPO) mediated system has been developed for the synthesis of secondary amides with good to excellent yields in a single step. This unprecedented cascade process involves sequential reduction of N-O bond and benzoylation followed by dealkylation of N-C bond ofO-benzoylhydroxylamines (O-BHA). The methodology is versatile as it tolerates a variety of aromatic and aliphaticO-BHA as substrates to access secondary amides.

}, keywords = {Amides, Cascade reactions, O-Benzoylhydroxylamines, Redox reactions, synthetic methods}, issn = {1434-193X}, doi = {10.1002/ejoc.202000611, Early Access Date = JUN 2020}, author = {Aegurla, Balakrishna and Mandle, Ram D. and Shinde, Prasad G. and Parit, Ratan S. and Kamble, Sanjay P. and Sudalai, Arumugam and Senthilkumar, Beeran} } @article {48128, title = {Interplay of anion-pi(+) and pi(+)-pi(+) interactions in novel pyrido[2,1-a]isoquinolinium-based aiegens - substituent- and counterion-dependent fluorescence modulation and applications in live cell mitochondrial imaging}, journal = {Chemistry-A European Journal}, volume = {28}, year = {2022}, month = {JUL }, pages = {e202200632}, type = {Article}, abstract = {

Recently, the concept of anion-pi(+) interactions has witnessed unique applications in the field of AIEgen development. In this contribution, we disclose a consolidated study of a library of N-doped ionic AIEgens accessed through silver-mediated cyclization of pyridino-alkynes. A thorough photophysical, computational and crystallographic study has been conducted to rationalize the observed substituent- and counterion-dependent fluorescence properties of these luminogens. We further elucidate the prominent role of anion-pi(+) interactions, pi(+)-pi(+) interactions and other non-covalent interactions, in inhibiting the undesired ACQ effect. Finally, we have also demonstrated the application of selected AIEgens for imaging of mitochondria in live cells.

}, keywords = {1-a]isoquinolinium, AIEgens, anion-pi(+), crystal structure, mitochondrial imaging, pyrido[2}, issn = {0947-6539}, doi = {10.1002/chem.202200632}, author = {Mule, Ravindra D. and Roy, Rupam and Mandal, Koushik and Chopra, Deepak and Dutta, Tanoy and Sancheti, Shashank P. and Shinde, Popat S. and Banerjee, Somsuvra and Lal Koner, Apurba and Bhowal, Rohit and Senthilkumar, Beeran and Patil, Nitin T.} }