@article { ISI:000226669000004, title = {New bis-andrographolide ether from androgphis paniculata nees and evaluation of anti-HIV activity}, journal = {Natural Product Research}, volume = {19}, number = {3}, year = {2005}, month = {APR}, pages = {223-230}, publisher = {TAYLOR \& FRANCIS LTD}, type = {Article}, address = {4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}, abstract = {

Novel bis-andrographolide ether (1) and six known compounds andrographolide, 14-deoxy-11,12-didehydroandrographolide, andrograpanin, 14-deoxyandrographolide, (+/-)-5- hydroxy-7,8-dimethoxyflavanone, and 5-hydroxy-7,8-dimethoxyflavone have been isolated from the aerial parts of Andrographis paniculota and their structures were established by spectral data. All the isolates were tested for the anti-HIV and cytotoxic activity.

}, keywords = {Acanthaceae, Andrographis paniculata, anti-HIV, bis-andrographolide ether, Cytotoxic activity}, issn = {1478-6419}, doi = {10.1080/14786410410001709197}, author = {Reddy, V. L. N. and Reddy, S. M. and Ravikanth, V. and Krishnaiah, P. and Goud, T. V. and Rao, T. P. and Ram, T. S. and Gonnade, Rajesh G. and Bhadbhade, Mohan M. and Venkateswarlu, Y} } @article { ISI:000344459400014, title = {N-Heterocyclic carbene-catalyzed enantioselective synthesis of functionalized cyclopentenes via alpha,beta-unsaturated acyl azoliums}, journal = {Chemical Communications}, volume = {50}, number = {93}, year = {2014}, month = {OCT}, pages = {14539-14542}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Highly enantioselective NHC-organocatalyzed synthesis of functionalized cyclopentenes proceeding via alpha,beta-unsaturated acyl azolium intermediates is reported. The organocascade reaction of modified enals with malonic ester derivatives having a gamma-benzoyl group involves the Michael-intramolecular aldol-beta-lactonization-decarboxylation sequence to deliver cyclopentenes in good yields and excellent ee values.

}, issn = {1359-7345}, doi = {10.1039/c4cc07433e}, author = {Mondal, Santigopal and Yetra, Santhivardhana Reddy and Patra, Atanu and Kunte, Sunita S. and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {42434, title = {N-Heterocyclic carbene-catalyzed diastereoselective synthesis of β-lactone-fused cyclopentanes using homoenolate annulation reaction}, journal = {Chemical Communications}, volume = {51}, year = {2015}, month = {MAY}, pages = {9559-9562}, abstract = {

NHC-catalyzed annulation of enals with 2-enoylpyridines or 2-enoylpyridine\ N-oxides leading to the diastereoselective synthesis of β-lactone-fused cyclopentanes is reported. The reaction proceeds\ via\ the generation of homoenolate equivalent intermediates and tolerates a broad range of functional groups.

}, doi = {10.1039/C5CC02960K}, author = {Mukherjee, Subrata and Mondal, Santigopal and Patra, Atanu and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article { ISI:000362436800028, title = {Novel one-pot multi-component synthesis of 3,3 {\textquoteleft}-disubstituted oxindole and spirooxindole scaffolds via Sn-catalyzed C(sp(3))-H functionalization of azaarenes by sequential Knoevenagel-Michael-cyclization reaction}, journal = {RSC Advances}, volume = {5}, number = {99}, year = {2015}, month = {SEP}, pages = {81103-81107}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Sn-catalyzed C(sp(3))-H bond functionalization of 2-methyl azaarenes/2-(azaaryl)methanes has been achieved for the first time in a one-pot multi-component reaction with isatin and active methylene compounds via tandem sequential Knoevenagel-Michael-intramolecular C-N cyclization. This strategy provides new cost-effective access to potent and biologically/medicinally important spirooxindoles/3,3{\textquoteright}-disubstituted 2-oxindoles in good to excellent yields.

}, issn = {2046-2069}, doi = {10.1039/c5ra16334j}, author = {Chavan, Santosh S. and Pathan, Mohsinkhan Y. and Thorat, Shridhar H. and Gonnade, Rajesh G. and Mulla, Shafeek Abdul Rashid} } @article { ISI:000374073800014, title = {Naphthoquinone based chemosensor 2-(2 {\textquoteleft}-aminoethylpyridine)-3-chloro-1,4-naphthoquinone: detection of metal ions, X-ray -crystal structures and DFT studies}, journal = {Journal of Molecular Structure}, volume = {1114}, year = {2016}, month = {JUN}, pages = {132-143}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Naphthoquinone based Chemosensor 2; 2-(2{\textquoteright}-aminoethylpyridine)-3-chloro-1,4-napthoquinone have been synthesized and characterized. Chemosensor 2 crystallizes in the orthorhombic space group Pbcn and shows extensive intramolecular as well as intermolecular hydrogen bonding interactions. Each molecule of Chemosensor 2 showed interaction with five neighboring molecules via C-H center dot center dot center dot N, N-H center dot center dot center dot N, C-H center dot center dot center dot Cl and C-H center dot center dot center dot O interactions. Slipped pi-pi stacking interaction was observed in adjacent quinonoid and benzenoid rings. Chemosensor abilities of Chemosensor 2 ligand have been evaluated with metal ions viz. Cu2+, Ni2+, Zn2+, Co2+, Fe3+, Mn2+, Cr3+, Hg2+, La3+ and Cd2+ in methanol, methanol-water mixture and in presence of mild base triethylamine. Stoichiometry of Chemosensor 2 with metal ions such as Cu2+, Ni2+, Zn2+ and Co2+ ions was determined by Jobs method in methanol and were found as 1:1 for Cu2+ and 2:1 for Ni2+, Zn2+ Co2+. The variation in the metal ligand ratio is observed in aqueous media for Cu2+. Chemosensor 2 can be used selectively for naked eye detection of Cu2+ ions. The association constant obtained in methanol shows the trend Cu2+\>Ni2+\>Co2+. Cu2+ and two (Ni-1 and Ni-2) Ni2+ complexes were synthesized. Ni-2 complex showed coordination of Chemosensor 2 ligands was through pyridine nitrogen{\textquoteright}s only. The Chemosensor 2 and its deprotonated forms in methanol, water and triethylamine were also studied by TD-DFT studies. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {Aminonaphthoquinone, Chemosensor, hydrogen bonding, Naphthoquinone, pi-pi stacking, TD-DFT}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2016.02.065}, author = {Patil, Amit and Ware, Anuja P. and Bhand, Sujit and Chakravarty, Debamitra K. and Gonnade, Rajesh G. and Pingale, Subhash S. and Salunke-Gawali, Sunita} } @article {46112, title = {Neutral imino-methyl benzenesulfonate-ligated Pd(II) complexes and implications in ethylene polymerization}, journal = {ACS Omega}, volume = {4}, year = {2019}, month = {MAY}, pages = {9502-9511}, type = {Article}, abstract = {

A reaction between sodium 2-formylbenzenesulfonate and aniline revealed the near-quantitative (91\%) formation of sodium-2-((phenylimino)methyl)benzenesulfonate L1. The identity of L1 was unambiguously ascertained using spectroscopic and analytical methods. The scope of this methodology was widened and various electron-donating amines were treated with sodium 2-formylbenzenesulfonate, and a small library of 6 imine ligands L2-L6 was generated. When L2 was treated with [(COD)PdMeCI], instead of the anticipated [L2PdMe(DMSO)] complex, the formation of [(DMSO)(2)Pd2Cl2Me2] Pd Dim was observed. Nevertheless, the desired imino-methyl benzenesulfonate-ligated palladium complex [L2PdMe(Lu)] C1 was obtained by in situ abstraction of chloride and addition of bulky 2,6-lutidine as the donor group. The observation of characteristic Pd-Me protons at 0.06 ppm and the corresponding carbon at -8.1 ppm indicated the formation of C1. These 1D NMR observations were corroborated by 2D C-H correlation spectra and mass analysis, and the existence of C1 was unambiguously ascertained. Along the same lines, L4 and L5 were treated with a palladium precursor to produce [L4/SPdMe(Lu)]-type complexes C2-C3 in 55-84\% yield, and their identity was established by using a combination of spectroscopic tools, analytical methods, and single-crystal X-ray diffraction. The synthetic utility of C1-C3 has been demonstrated by utilizing these complexes in the insertion polymerization of ethylene to polyethylene.

}, issn = {2470-1343}, doi = {10.1021/acsomega.9b00709}, author = {Deshmukh, Satej S. and Gaikwad, Shahaji R. and Mote, Nilesh R. and Manod, M. and Gonnade, Rajesh G. and Chikkali, Samir H.} } @article {46021, title = {N-Heterocyclic carbene-catalyzed umpolung of imines for the enantioselective synthesis of dihydroquinoxalines}, journal = {ACS Catalysis}, volume = {9}, year = {2019}, month = {MAY}, pages = {4065-4071}, type = {Article}, abstract = {

N-heterocyclic carbene (NHC) organocatalysis is widely employed for the umpolung of aldehydes and recently to the umpolung of Michael acceptors and aldimines. Described herein is the NHC-organocatalyzed umpolung of aldimines for the enantioselective synthesis of nitrogen heterocycles. The bisimines generated from the condensation of 1,2-phenylenediamines and salicylaldehydes undergo intramolecular cyclization in the presence of a chiral NHC catalyst, resulting in the formation of dihydroquinoxalines in moderate to good yields and er values. Detailed DFT studies shed light on the role of -OH groups in stabilizing the initially generated aza-Breslow intermediates via intramolecular hydrogen bonds. Preliminary photophysical studies on the synthesized dihydroquinoxalines revealed that these molecules can be used for the sensing of various acids and bases.

}, keywords = {dihydroquinoxalines, imines, N-heterocyclic carbenes, organocatalysis, umpolung}, issn = {2155-5435}, doi = {10.1021/acscatal.9b00737}, author = {Das, Tamal Kanti and Ghosh, Avik and Balanna, Kuruva and Behera, Pradipta and Gonnade, Rajesh G. and Marelli, Udaya Kiran and Das, Abhijit Kumar and Biju, Akkattu T.} } @article {47386, title = {NHC-catalyzed desymmetrization of N-aryl maleimides leading to the atroposelective synthesis of N-Aryl succinimides}, journal = {Angewandte Chemie-International Edition}, volume = {60}, year = {2021}, month = {MAY }, pages = {12264-12268}, type = {Article}, abstract = {

Although the construction of axially chiral C-C bonds leading to the atroposelective synthesis of biaryls and allied compounds are well-known, the related synthesis of compounds bearing axially chiral C-N bonds are relatively rare. Described herein is the N-heterocyclic carbene-catalyzed atroposelective synthesis of N-aryl succinimides having an axially chiral C-N bond via the desymmetrization of N-aryl maleimides. The NHC involved intermolecular Stetter-aldol cascade of dialdehydes with prochiral N-aryl maleimides followed by oxidation afforded N-aryl succinimides in good yields and ee values. Preliminary studies on rotation barrier for the C-N bond, the temperature dependence, and detailed DFT studies on mechanism are also provided.

}, keywords = {asymmetric catalysis, axial chirality, desymmetrization, N-heterocyclic carbenes, organocatalysis}, issn = {1433-7851}, doi = {10.1002/anie.202016938, Early Access Date = APR 2021}, author = {Barik, Soumen and Shee, Sayan and Das, Soumik and Gonnade, Rajesh G. and Jindal, Garima and Mukherjee, Subrata and Biju, Akkattu T.} } @article {47638, title = {Ni(II)-catalyzed intramolecular C-H/C-H oxidative coupling: an efficient route to functionalized cycloindolones and indenoindolones}, journal = {ACS Catalysis}, volume = {11}, year = {2021}, month = {OCT }, pages = {12384-12393}, type = {Article}, abstract = {Nickel(II)-catalyzed intramolecular C(sp(2))-H/C(sp(3))-H and C(sp(2))-H/C(sp(2))-H oxidative couplings in indoles are achieved via chelation assistance. These reactions provide access to biologically relevant five- and six-membered substituted cyclopentaindolones, carbazolones, and indenoindolones in high yields and good chemoselectivity employing an air-stable and defined nickel catalyst, (bpy)Ni(OAc)(2). The oxidative cyclizations proceeded either through a six-membered or an unconventional seven-membered nickelacycle. An extensive mechanistic investigation by experiments and theoretical calculations revealed a facile indole{\textquoteright}s C(2)-H nickelation and a rate-limiting reductive elimination process. This intramolecular oxidative cyclization operates via a probable Ni(II)/Ni(III) pathway involving single-electron oxidation of nickel without the participation of a carbon-based radical.}, keywords = {C-H activation, cycloindolones, indenoindolones, indoles, Mechanism, Nickel, oxidative coupling}, issn = {2155-5435}, doi = {10.1021/acscatal.1c03314}, author = {Ankade, Shidheshwar B. and Samal, Pragnya Paramita and Soni, Vineeta and Gonnade, Rajesh G. and Krishnamurty, Sailaja and Punji, Benudhar} } @article {48175, title = {Novel crystal forms of Entresto: a supramolecular complex of trisodium sacubitril/valsartan hemi-pentahydrate}, journal = {Crystengcomm}, volume = {24}, year = {2022}, month = {OCT}, pages = {7387-7393}, type = {Article}, abstract = {

Entresto is a salt-cocrystal supramolecular complex with the chemical name trisodium sacubitril/valsartan hemi-pentahydrate for treating chronic heart failure and was approved by the US FDA in 2015. This multidrug complex was synthesized in our laboratory to investigate its polymorphic behavior. Different crystallization conditions, including various solvent systems, yielded different novel solid forms of Entresto (Form-I to Form-VI), including the reported form. All the novel solids are solvent-dependent and were reproducibly crystallized on a 10 g scale quantity. The 1H NMR spectra confirmed the 1 : 1 stoichiometry of the two drugs, namely, sacubitril and valsartan, in all the solid forms of the crystalline products. Powder X-ray diffraction and DSC analysis of the crystalline solids established that they are distinct crystalline forms. Stability studies under ambient conditions carried out over a one-year period showed higher stability for Form-I and Form-III compared to the other forms, including the innovator crystal form (labelled as Form-II). The novel crystal forms (notably Form-I and Form-III) exhibit higher stability and less hygroscopicity than the reported Form-II.

}, doi = {10.1039/d2ce01009g}, author = {Shaikh, Tabrez R. and George, Christy P. and Bhukya, Priyanka and Shelke, Nikita and Pawar, Komal and Garai, Abhijit and Dandela, Rambabu and Gonnade, Rajesh G. and Nangia, Ashwini K.} } @article {48760, title = {NHC-catalyzed enantioselective synthesis of tetracyclic δ-lactones by (4+2) annulation of ortho-quinodimethanes with activated ketones}, journal = {Organic Letters}, volume = {25}, year = {2023}, month = {OCT }, pages = {7852-7857}, type = {Article}, abstract = {

The N-heterocyclic carbene (NHC)-catalyzed generation of ortho-quinodimethanes (o-QDMs) from 9H-fluorene-1-carbaldehydes followed by the interception with activated ketones resulting in the enantioselective synthesis of tetracyclic delta-lactones is presented. High diastereoselectivity of products, remote C-(sp(3))-H functionalization, broad substrate scope, and mild reaction conditions are the notable features of the present (4 + 2) annulation.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.3c03076}, author = {Sarkar, Deeptanu and Barik, Shilpa and Shee, Sayan and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {48752, title = {N-heterocyclic carbene-catalyzed atroposelective synthesis of N-N axially chiral 3-amino quinazolinones}, journal = {ACS Catalysis}, volume = {13}, year = {2023}, month = {JUN }, pages = {8752-8759}, type = {Article}, abstract = {

Although the atroposelective synthesisof biaryls and related compoundsbearing axially chiral C-C bonds is well-known, the synthesisof axially chiral C-N bond-containing compounds is relativelyless explored, and the construction of axially chiral N-N bondshas received only scant attention. Demonstrated herein is the N-heterocycliccarbene (NHC)-catalyzed selective amidation reaction, leading to theatroposelective synthesis of N-N axially chiral 3-amino quinazolinones.The NHC-catalyzed reaction of quinazolinones containing a free N-Hmoiety with \& alpha;,\& beta;-unsaturated aldehydes under oxidativeconditions furnished the atropisomeric quinazolinone derivatives undermild conditions and broad scope. Preliminary studies on experimentaland density functional theory-based N-N rotational barrierdetermination are also presented.

}, keywords = {amino quinazolinones, asymmetriccatalysis, axial chirality, N-heterocycliccarbenes, organocatalysis}, issn = {2155-5435}, doi = {10.1021/acscatal.3c01709}, author = {Balanna, Kuruva and Barik, Soumen and Barik, Shilpa and Shee, Sayan and Manoj, Niket and Gonnade, Rajesh G. and Biju, Akkattu T.} }