01515nas a2200157 4500008004100000245006600041210006600107260000800173300001400181490000700195520098700202100002701189700002201216700001801238856010101256 2017 eng d00aBronsted acid catalyzed enantioselective pericyclic reactions0 aBronsted acid catalyzed enantioselective pericyclic reactions cJUL a4023-40380 v733 aPericyclic reactions can be challenging processes to render asymmetric, due to the concerted and non polar nature of the transition states. Several examples have been reported in which a suitable catalyst binds to a heteroatom-containing substituent in the substrate and accelerates the reaction rate. The requirement of coordinating functionalized substrates has limited the generality of such asymmetric transformations. Multifunctional Bronsted acids are promising catalysts that represent a new paradigm in asymmetric pericyclic reactions. These chiral catalysts rely on multiple non-covalent interactions in the transition state for asymmetric induction, which has been utilized to activate more general substrate classes. In this review, we will cover recent advances in Bronsted acid catalyzed pericyclic reactions and discuss the impact of catalyst design on the expansion of substrate scope for highly enantioselective processes. (C) 2017 Elsevier Ltd. All rights reserved.1 aSleet, Christopher, E.1 aTambar, Uttam, K.1 aMaity, Pradip uhttps://library.ncl.res.in/content/bronsted-acid-catalyzed-enantioselective-pericyclic-reactions01096nas a2200157 4500008004100000245014700041210006900188260000800257300001400265490000700279520046400286100002100750700001800771700001900789856013000808 2017 eng d00aTransition metal, azide, and oxidant-free homo- and heterocoupling of ambiphilic tosylhydrazones to the regioselective triazoles and pyrazoles0 aTransition metal azide and oxidantfree homo and heterocoupling o cAPR a1534-15370 v193 aWith N-tosylhydrazone as an ambiphilic reagent, an unprecedented cyclization reaction of two identical or different tosylhydrazones has been developed to access various 4,5-disubstituted-2H-triazoles under transition metal, azide, and oxidant-free conditions. A mechanistic.rationalization study led to the identification of several electronically diverse unsaturated systems for regioselective synthesis of 1- and 2-substituted 1,2,3-triazoles and pyrazoles.1 aPanda, Subhankar1 aMaity, Pradip1 aManna, Debasis uhttps://library.ncl.res.in/content/transition-metal-azide-and-oxidant-free-homo-and-heterocoupling-ambiphilic-tosylhydrazones00994nas a2200169 4500008004100000022001400041245010700055210006900162260000800231300001400239490000700253520038200260100001900642700001600661700001800677856012900695 2018 eng d a1477-052000aOrganocatalyst bound -aminoalkyl radical intermediate for controlled aerobic oxidation of iminium ions0 aOrganocatalyst bound aminoalkyl radical intermediate for control cJUL a5081-50850 v163 a

A catalyst bound -aminoalkyl radical intermediate from iminium is developed to control its formation and reactivity with aerobic oxygen. The influence of the catalyst was demonstrated via the ease of radical intermediate formation and its subsequent reactivity, including the first catalyst-controlled enantioselective aerobic oxidation with a chiral phosphite catalyst.

1 aMotaleb, Abdul1 aBera, Asish1 aMaity, Pradip uhttps://library.ncl.res.in/content/organocatalyst-bound-aminoalkyl-radical-intermediate-controlled-aerobic-oxidation-iminium00959nas a2200169 4500008004100000022001400041245008900055210006900144260000800213300001400221490000700235520036700242100002200609700002000631700001800651856012000669 2018 eng d a1477-052000aRemovable functional group strategy for regiodivergent Wittig rearrangement products0 aRemovable functional group strategy for regiodivergent Wittig re cDEC a8922-89260 v163 a1,2] and [2,3] Wittig rearrangements are competing reaction pathways, often leading to uncontrollable product distribution. We employ a single removable functional group to fulfill the dual role of attaining a reversible [2,3] and stabilizing radical intermediate for the [1,2] path to obtain both the Wittig products selectively for a broad range of substrates.1 aAlam, Md, Nirshad1 aLakshmi, K., M.1 aMaity, Pradip uhttps://library.ncl.res.in/content/removable-functional-group-strategy-regiodivergent-wittig-rearrangement-products01231nas a2200193 4500008004100000022001400041245013800055210006900193260000900262300001400271490000700285520050400292100002300796700001800819700002300837700002000860700002600880856013100906 2019 eng d a1523-706000aAllenoate prenucleophiles: a triply diastereoselective approach to beta-hydroxy esters containing all-carbon alpha-quaternary centers0 aAllenoate prenucleophiles a triply diastereoselective approach t cOCT  a7952-79550 v213 a

Allenyl esters activated by titanium(IV) underwent additions to a wide range of aldehydes in high regio- and diastereoselectivities leading to products containing an all carbon quaternary center bearing an alpha-vinyl group that was installed with high selectivity for the Z-geometry. An aldol product was also converted to an indanone offering a new route to this important compound class. Product triple diastereoselectivity has been rationalized using a concerted transition-state model.

1 aMaki, Samantha, L.1 aMaity, Pradip1 aDougherty, Shannon1 aJohns, Jennifer1 aLepore, Salvatore, D. uhttps://library.ncl.res.in/content/allenoate-prenucleophiles-triply-diastereoselective-approach-beta-hydroxy-esters-containing02105nas a2200157 4500008004100000245010900041210006900150260000800219520149800227100001901725700001701744700001501761700002401776700001801800856012901818 2019 eng d00a Phosphite-Catalyzed C-H allylation of azaarenes via an enantioselective [2,3]-Aza-wittig rearrangement 0 aPhosphiteCatalyzed CH allylation of azaarenes via an enantiosele cAUG3 a

A phosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio- and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo a stereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C-H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.

1 aMotaleb, Abdul1 aRani, Soniya1 aDas, Tamal1 aGonnade, Rajesh, G.1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-catalyzed-c-h-allylation-azaarenes-enantioselective-23-aza-wittig-rearrangement01323nas a2200217 4500008004100000022001400041245009400055210006900149260000900218300001200227490000700239520058600246100002200832700002500854700002300879700002000902700002600922700001700948700001800965856012200983 2021 eng d a1523-706000a[1,3]-Claisen rearrangement via removable functional group mediated radical stabilization0 a13Claisen rearrangement via removable functional group mediated  cFEB  a890-8950 v233 a

A thermal O-to-C [1,3]-rearrangement of alpha-hydroxy acid derived enol ethers was achieved under mild conditions. The 2-aminothiophenol protection of carboxylic acids facilitates formation of the [1,3] precursor and its thermal rearrangement via stabilization of a radical intermediate. Experimental and theoretical evidence for dissociative radical pair formation, its captodative stability via aminothiophenol, and a unique solvent effect are presented. The aminothiophenol was deprotected from rearrangement products as well as after derivatization to useful synthons.

1 aAlam, Md, Nirshad1 aDash, Soumya, Ranjan1 aMukherjee, Anirban1 aPandole, Satish1 aMarelli, Udaya, Kiran1 aVanka, Kumar1 aMaity, Pradip uhttps://library.ncl.res.in/content/13-claisen-rearrangement-removable-functional-group-mediated-radical-stabilization01692nas a2200205 4500008004100000022001400041245011200055210006900167260000800236300001400244490000700258520097800265100001701243700002501260700001601285700002201301700001701323700001801340856012801358 2021 eng d a2041-652000aPhosphite mediated asymmetric N to C migration for the synthesis of chiral heterocycles from primary amines0 aPhosphite mediated asymmetric N to C migration for the synthesis cJUL a8996-90030 v123 aA phosphite mediated stereoretentive C-H alkylation of N-alkylpyridinium salts derived from chiral primary amines was achieved. The reaction proceeds through the activation of the N-alkylpyridinium salt substrate with a nucleophilic phosphite catalyst, followed by a base mediated [1,2] aza-Wittig rearrangement and subsequent catalyst dissociation for an overall N to C-2 alkyl migration. The scope and degree of stereoretention were studied, and both experimental and theoretical investigations were performed to support an unprecedented aza-Wittig rearrangement-rearomatization sequence. A catalytic enantioselective version starting with racemic starting material and chiral phosphite catalyst was also established following our understanding of the stereoretentive process. This method provides efficient access to tertiary and quaternary stereogenic centers in pyridine systems, which are prevalent in drugs, bioactive natural products, chiral ligands, and catalysts.1 aRani, Soniya1 aDash, Soumya, Ranjan1 aBera, Asish1 aAlam, Md, Nirshad1 aVanka, Kumar1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-mediated-asymmetric-n-c-migration-synthesis-chiral-heterocycles-primary-amines01915nas a2200193 4500008004100000022001400041245010900055210006900164260000800233300001600241490000800257520123200265100001801497700002301515700002201538700001801560700001801578856012501596 2022 eng d a1520-610600aBlue fluorescence of cyano-tryptophan predicts local electrostatics and hydrogen bonding in biomolecules0 aBlue fluorescence of cyanotryptophan predicts local electrostati cDEC a10732-107400 v1263 a

Cyano-tryptophan is an unnatural fluorescent amino acid that emits in the visible region. Along with the structural similarity with tryptophan, the unique photophysical properties of this fluorophore make it an ideal probe for biophysical research. Herein, combining fluorescence spectroscopy, infrared spectroscopy, and molecular dynamics simulations, we show that the cyano-tryptophan's emission energy quantifies the underlying bond-specific noncovalent interactions in terms of the electric field. We further report the use of fluorophore's emission energy to predict its hydrogen bond characteristics. We demonstrate that combining experiments with molecular dynamics simulations can provide the hydrogen bonding status of the nitrile moiety. In addition, we report a method to differentiate between aqueous and nonaqueous hydrogen-bonding partners. Using a phenomenological approach, we demonstrate that the presence of the cyano-indole moiety is responsible for the distinct correlations between the fluorophore's emission and the electrostatic forces on the nitrile bond. As indole is a privileged scaffold for both native amino acids and nucleobases, cyano-indoles will have many multifaceted applications.

1 aHaldar, Tapas1 aChatterjee, Srijan1 aAlam, Md, Nirshad1 aMaity, Pradip1 aBagchi, Sayan uhttps://library.ncl.res.in/content/blue-fluorescence-cyano-tryptophan-predicts-local-electrostatics-and-hydrogen-bonding01350nas a2200181 4500008004100000022001400041245003900055210003800094260000800132300001400140490000700154520085500161100001901016700001601035700002801051700001801079856007101097 2023 eng d a1477-052000aC-H functionalization of pyridines0 aCH functionalization of pyridines cJUL a5671-56900 v213 a

Pyridine and its reduced form (piperidine) are the most common nitrogen heterocycles in FDA-approved drugs. Additionally, their presence in alkaloids, ligands for transition metals, catalysts, and organic materials with various properties makes them among the most important structural cores. Despite its importance, direct and selective functionalization of pyridine remains scarce due to its electron-poor nature and nitrogen coordination power. Instead, functionalized pyridine rings were primarily constructed from suitably substituted acyclic precursors. The focus on sustainable chemistry with minimum waste generation encourages chemists to develop direct C-H functionalization. This review summarizes different approaches to tackle the reactivity and regio- and stereoselectivity aspects for direct pyridine C-H functionalization.

1 aMaity, Susmita1 aBera, Asish1 aBhattacharjya, Ayantika1 aMaity, Pradip uhttps://library.ncl.res.in/content/c-h-functionalization-pyridines02281nas a2200253 4500008004100000022001400041245012000055210006900175260000800244300001100252490000800263520142300271653001701694653002801711653002601739653001001765653002801775100002001803700001901823700001801842700001801860700001701878856013201895 2023 eng d a0021-899500aControlled synthesis of thermosensitive tunable porous film of (pNIPAM)-b-(PCL) copolymer for sustain drug delivery0 aControlled synthesis of thermosensitive tunable porous film of p cMAY ae538540 v1403 a

There have been reports on different types of porous polymer films for various applications. The designing of such porous films with uniform properties is a challenging task. In this work, tunable porous thin films of poly(N-isopropylacrylamide) (pNIPAM) and polycaprolactone (PCL), that is, (pNIPAM)-b-(PCL) has been fabricated and its sustained drug delivery applications have been reported. First, the (pNIPAM)-b-(PCL) has been synthesized through the addition polymerization of pNIPAM and PCL. Then the synthesized (pNIPAM)-b(PCL) has been used to design porous thin film with varying temperatures without using any external template, below and above the lower critical solution temperatures (LCST) of pNIPAM. Pore size in (pNIPAM)-b-(PCL) films has been tuned by varying the temperature from similar to 10 to 40 degrees C. Then the developed thermosensitive porous film has been taken and seeded with the K562 (chronic myeloid leukemia blood cancer) and HepG2 (hepatocarcinoma) cells and the skin cancer cells (B16-F10) killing efficiency of anticancer drug (e.g., doxorubicin hydrochloride, DOX) loaded (pNIPAM)-b-(PCL) film has been studied. It is found that the DOX-loaded (pNIPAM)-b-(PCL) can efficiently kill the skin cancer cells. The porous polymer thin film reported in this work can be a versatile platform for the loading of drugs and it can be used for the various therapeutic applications.

10aBiomaterials10aBiomedical Applications10adrug delivery systems10afilms10ananostructured polymers1 aAmgoth, Chander1 aPatra, Sukanya1 aWasnik, Kirti1 aMaity, Pradip1 aPaik, Pradip uhttps://library.ncl.res.in/content/controlled-synthesis-thermosensitive-tunable-porous-film-pnipam-b-pcl-copolymer-sustain-drug01273nas a2200229 4500008004100000022001400041245006800055210006700123260000800190490000700198520059100205653001600796653002300812653001300835653002000848653001400868100001900882700001700901700001800918700001800936856008900954 2023 eng d a1434-193X00aOrganophosphites: an addition to the arsenal of organocatalysts0 aOrganophosphites an addition to the arsenal of organocatalysts cJAN0 v263 a

Organophosphites are nucleophilic in nature and can act as a good leaving group owing to the stability of the phosphite anion. This dual reactivity makes them good candidates for nucleophilic organocatalysis. However, phosphites were introduced only in 2004 as the umpolung catalyst for acylsilane substrates utilizing sequential Brook rearrangements. Very recently, phosphites have been reported to catalyze aza-rearrangements and radical reactions. In this review, we discuss the reactivity parameters to understand its lack of use, as well as the potential for catalysis.

10aacylradical10aazaacyl equivalent10acylanion10aorganocatalysis10aphosphite1 aBaral, Nilofar1 aRani, Soniya1 aSaikia, Pinku1 aMaity, Pradip uhttps://library.ncl.res.in/content/organophosphites-addition-arsenal-organocatalysts01773nas a2200229 4500008004100000022001400041245019600055210006900251260000900320300001400329490000700343520089800350100002101248700002201269700002601291700002301317700001501340700001801355700001901373700002101392856013001413 2024 eng d a0022-326300a2-Pyridone-directed CuII-catalyzed general method of C(sp2)-H activation for C-S, C-Se, and C-N cross-coupling: easy access to aryl thioethers, selenide ethers, and sulfonamides and DFT study0 a2Pyridonedirected CuIIcatalyzed general method of Csp2H activati cAPR  a6798-68120 v893 a

We have demonstrated N-substituted 2-pyridones as an N,O-directing group for selective C(sp(2))-H-activated thiolation, selenylation, and sulfonamidation of ortho C-H bonds of benzamides. This method utilizes a cost-effective Cu(II)-salt catalyst instead of precious metal catalysts, achieving high yields, including gram-scale synthesis and excellent functional group tolerance. We applied this protocol to access 30 different compounds with high yields, demonstrating thiolation of fluorine-substituted benzamides as well. Density functional theory (DFT) calculations support the mechanism, including acetate-supported concerted metalation deprotonation (CMD) steps and the unique role of dimethyl sulfoxide (DMSO) solvent. The facile synthesis of pharmaceutically important sulfonamides and other compounds highlights the method's potential in chemistry and medicinal chemistry.

1 aPati, Tanmay, K.1 aMolla, Sabir, Ali1 aGhosh, Narendra, Nath1 aKundu, Mrinalkanti1 aAjarul, Sk1 aMaity, Pradip1 aKhamrai, Uttam1 aMaiti, Dilip, K. uhttps://library.ncl.res.in/content/2-pyridone-directed-cuii-catalyzed-general-method-csp2-h-activation-c-s-c-se-and-c-n-cross01392nas a2200169 4500008004100000245013700041210006900178260000800247300001400255490000700269520072500276100002501001700002201026700001801048700002601066856013001092 2025 eng d00aAnionic 5-endo-dig cyclizations: an experimental investigation of in-plane aromaticity involving a non-enolate carbanion nucleophile0 aAnionic 5endodig cyclizations an experimental investigation of i cNOV a6609-66130 v123 a

Cyclitive additions of aliphatic carbanions to non-electrophilic carbon-carbon triple bonds under mild, transition-metal-free conditions are described for the first time. These results confirm theoretical models that invoke in-plane aromaticity to predict the favorability of 5-endo-dig reactions in these systems. In contrast to related Conia-ene cyclizations (5-enolexo-endo-dig), our results generally led to cyclic and allene products in near parity ratios across a broad range of substrates, suggesting that cyclization may proceed via an early ambimodal transition state. Experimental results are presented with a view to refining existing mechanistic models for this growing class of alkyne reactions.

1 aNugent, Kristina, M.1 aHintze, Silas, Q.1 aMaity, Pradip1 aLepore, Salvatore, D. uhttps://library.ncl.res.in/content/anionic-5-endo-dig-cyclizations-experimental-investigation-plane-aromaticity-involving-non02241nas a2200217 4500008004100000022001400041245015800055210006900213260000800282300001400290490000700304520143800311100001701749700002101766700003001787700002801817700001701845700001601862700001801878856012701896 2025 eng d a2041-652000aPhosphite mediated molecular editing via switch to meta-C-H alkylation of isoquinolines: emergence of a distinct photochemical [1,3] N to C rearrangement0 aPhosphite mediated molecular editing via switch to metaCH alkyla cJAN a1809-18180 v163 a

The isoquinoline core is present in one of the largest subsets of bioactive natural products. The multifunctional isoquinoline core exerts diverse bioactivity, resulting in the development of numerous isoquinoline-based drugs and molecules that are currently under clinical trials. We developed a new approach for phosphite-mediated [1,2] alkyl migration for an overall ortho-C-H alkylation via N-alkylation of isoquinoline. Tuning the phosphite-mediated protocol to switch the site selectivity would expedite direct and diverse multi-C-H bond functionalization. We report a new approach starting with a simple N-alkylation of isoquinoline with sterically and electronically diverse alkyl bromides for their phosphite-mediated photochemical [1,3] N to C rearrangement followed by a rearomatization sequence that leads to meta-C-H (C4) alkylation. Combined experimental and computational studies unveiled the emergence of an unprecedented C-N bond cleavage pathway from the singlet excited state of the enamine-type intermediate. Our radical bond-cleavage pathway favors substituted alkyl group migration that complements the recently successful meta-alkylation methods with smaller and more reactive electrophiles. This switch in site selectivity via tuning the phosphite-mediated protocol resulted in sequential C-H difunctionalization of isoquinoline including regiodivergent ortho, meta-dialkylations of isoquinolines.

1 aRani, Soniya1 aRay, Anuj, Kumar1 aDewangan, Devendra, Kumar1 aPatil, Nita, Aruna Ramc1 aAarthika, M.1 aPaul, Ankan1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-mediated-molecular-editing-switch-meta-c-h-alkylation-isoquinolines-emergence02180nas a2200265 4500008004100000022001400041245014600055210006900201260000800270490000600278520120700284653002501491653001901516653002701535653003001562653002701592100003101619700002001650700003001670700002401700700001601724700001801740700002701758856012901785 2025 eng d a2366-748600aRational design of reduced graphene oxide/TiO2/gold nanorod nanocomposite for complete degradation of polystyrene microplastics in wastewater0 aRational design of reduced graphene oxideTiO2gold nanorod nanoco cAUG0 v93 a

Our planet is being devoured by plastic consumption every day. Water, soil, and air are deliberately polluted by the ingredients of these nondegradable plastics. Extensive usage of plastic has serious consequences in the environment, wildlife, and human health. A comprehensive approach to eradicate plastics from the planet is therefore imperative. Herein, a ternary nanocomposite subsumed of reduced graphene oxide (rGO), titanium dioxide (TiO2), and gold nanorods (AuNRs) is synthesized and effectively deployed to remove plastics from water as well as degradation of polymer film by both chemically and photocatalytically. The hydrothermally prepared nanocomposite completely removes polystyrene molecules from water, and 1.2 mg of plastic degradation is observed during the photolysis. Conversely, chemical degradation pathway induces the weight loss of 10.7 mg. Both Plasmon-induced interfacial charge transfer transition (PICTT) and Plasmon-induced hot electron transfer (PHET) assist the formation of reactive oxygen species (ROS) that collectively degrades the polymer strands. The spectrochemical and microscopic studies validate the degradation studies with cautious conclusions.

10achemical degradation10aPhotocatalysis10aplasmonic hot electron10apolystyrene microplastics10aReduced graphene oxide1 aUshaVipinachandran, Varsha1 aNaveenkumar, K.1 aHaroon, Kabir, Hussain Ba1 aAshokan, Indhumathi1 aSinha, Arup1 aMaity, Pradip1 aBhunia, Susanta, Kumar uhttps://library.ncl.res.in/content/rational-design-reduced-graphene-oxidetio2gold-nanorod-nanocomposite-complete-degradation01560nas a2200253 4500008004100000022001400041245015100055210006900206260000900275300001400284490000700298520067500305100001800980700001700998700002801015700001901043700001901062700001601081700001801097700002401115700001701139700001801156856013201174 2025 eng d a1523-706000aUnified photoredox-catalyzed aerobic oxidative dynamic kinetic asymmetric transformation for C-N atropoisomers mediated by chiral organophosphites0 aUnified photoredoxcatalyzed aerobic oxidative dynamic kinetic as cAUG  a8171-81770 v273 a

The synthesis of anilides with a chiral C(=O)-N axis has relied on direct installation of the chiral C(sp2)-N(sp2) bond or enantioselective modification of the peripheral groups. However, these methods are constrained by the size and type of functional groups compatible with each strategy. Herein, we report a dynamic kinetic asymmetric transformation (DYKAT) for the aerobic oxidation of iminium ions to access C(=O)-N axial chirality that addresses those limitations. Furthermore, it eliminates the need for any auxiliary functional groups, which enables us to develop a unified method for the synthesis of atroposelective isoquinolone, lactam, and amide.

1 aSaikia, Pinku1 aAarthika, M.1 aBhattacharjya, Ayantika1 aMaity, Susmita1 aBajpai, Priyam1 aBera, Asish1 aSaha, Arindam1 aGonnade, Rajesh, G.1 aVanka, Kumar1 aMaity, Pradip uhttps://library.ncl.res.in/content/unified-photoredox-catalyzed-aerobic-oxidative-dynamic-kinetic-asymmetric-transformation-c-n