@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.} } @article {48977, title = {Synthesis of novel rhodamine type anthrone Spiro-lactam (ASL) analogues and evaluation of antiviral activity against dengue and chikungunya viruses}, journal = {European Journal of Medicinal Chemistry }, volume = {261}, year = {2023}, month = {DEC }, type = {Article}, abstract = {

A series of Rhodamine type Anthrone-Spirolactam (ASL) derivatives Benzylimin-Anthrone-Spirolactam (ASL-1 to ASL-10) and Benzamide-Anthrone-Spirolactam (ASL-11 and ASL-12) were synthesized via a simple condensation reaction between Anthrone Spiro-lactamine (2) and various aromatic aldehyde and acyl chlorides respectively. Since rhodamine-based compounds were reported to have antiviral activity, the ASL derivatives were examined for in vitro antiviral activity against dengue and chikungunya viruses. Among all the analogues, ASL-3, ASL-6, ASL-7, ASL-8, ASL-9 and ASL-10 were the most potent against dengue virus (DENV) and exerted around one log reduction in virus titre under post -treatment conditions. At the same time ASL-3 was effective under cotreatment conditions. Two analogues ASL-6 and ASL-12 exerted anti-chikungunya virus (CHIKV) activity under post -treatment conditions. In silico docking studies revealed that the ASL derivatives interacted with the proteins of DENV and CHIKV. Together, the results suggest the anti-DENV and CHIKV activity of ASL derivatives which may be exploited further for therapeutic purposes.

}, keywords = {Anthrone Spiro-lactam, Chikungunya virus, dengue virus, Rhodamine}, issn = {0223-5234}, doi = {10.1016/j.ejmech.2023.115849}, author = {Darole, Ratanamala S. and Bagad, Pooja K. and Gonnade, Rajesh G. and Alagarasu, Kalichamy and Punekar, Madhura and Shukla, Shridhar and Parashar, Deepti and Senthilkumar, Beeran} } @article {49092, title = {Br{\o}nsted acid- and Ni(ii)-catalyzed C-H oxidation/rearrangement of cyclotriveratrylenes (CTVs) to cyclic and acyclic quinones as potential anti-cancer agents}, journal = {Organic and biomolecular chemistry}, volume = {22}, year = {2024}, month = {JAN }, pages = {1038-1046}, type = {Article}, abstract = {

This paper describes a simple and practical protocol for the direct synthesis of acyclic and cyclic quinone derivatives via an acid-promoted nickel(ii)-catalyzed inner rim C-H oxidation of cyclotriveratrylene (CTV) and its analogues. The cyclic quinone derivatives resulted from trimethoxy-cyclotriveratrylene (TCTV) through C-C bond formation via intramolecular ipso substitution followed by subsequent anionic rearrangement containing stereo-vicinal quaternary centers. The DFT calculations strongly support the experimental findings and reveal the role of Bronsted acids in the C-H bond activation of CTV. All the newly synthesized compounds were screened for their in vitro anti-cancer activity using colorimetric SRB assay analysis. Among them, compounds 3a, 3d, 3h, 4a, 4b, 4c and 4e exhibited moderate anticancer activity against A549, HCT-116, PC-3, MDA-MB-231, HEK-293 and SW620 human cancer cell lines.

}, issn = {1477-0520}, doi = {10.1039/d3ob01428b}, author = {Darole, Ratanamala S. and Choudhary, Shailendra Singh and Sharma, Himanshu and Mali, Bhupendra P. and Gopu, Booblan and Vanka, Kumar and Senthilkumar, Beeran} } @article {49309, title = {Highly selective C-N and C-S dual functionalization of 1,3-dicarbonyl derivatives using TBHP as an oxidant}, journal = {Journal of Organic Chemistry}, volume = {89}, year = {2024}, month = {JUN}, pages = {9371-9380}, type = {Article}, abstract = {

A direct electrosynthesis/photocatalyst-free, atom-economical, and efficient method for the selective synthesis of (E)-3-amino-2-thiocyanato-alpha,beta-unsaturated carbonyl compounds is described through a given protocol. The present approach features the use of inexpensive ammonium thiocyanate to achieve dual functionalization of 1,3-dicarbonyl compounds using TBHP as an oxidant, providing a rapid and practical route to the selective formation of both C-N and C-S bonds via a radical process. This method offers a broad substrate scope with excellent yield and allows for further exploration of the products to construct heterocyclic compounds and other functionalities.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.4c00612}, author = {Bagad, Pooja K. and Darole, Ratanamala S. and Krishna, G. Rama and Senthilkumar, Beeran} } @article {49502, title = {Accessing polysubstituted 2-cyclopentenones via base-mediated annulation of β-keto esters and phenacyl bromides}, journal = {Organic \& Biomolecular Chemistry}, volume = {23}, year = {2025}, month = {MAY}, pages = {4519-4524}, type = {Article}, abstract = {

A transition metal-free method is demonstrated for the synthesis of polysubstituted 2-cyclopentenone compounds, which involves the direct annulation of phenacyl bromide with beta-keto esters in a single step. This process proceeds through a base-mediated SN2 nucleophilic substitution, followed by an intramolecular aldol condensation, resulting in the formation of three C-C bonds and one ring in a cascade manner. The experimental results achieved a record high yield of highly substituted diverse 2-cyclopentenone analogues, which exhibit very good structural resemblance to biologically significant natural compounds.

}, issn = {1477-0520}, doi = {10.1039/d4ob02088j}, author = {Kumar, Mohit and Paul, Vincent and Gamidi, Rama Krishna and Senthilkumar, Beeran} }