@article {42844, title = {Au(I)/Ag(I) co-operative catalysis: interception of Ag-bound carbocations with α-gold(I) enals in the imino-alkyne cyclizations with N-allenamides}, journal = {Chemical Communications}, volume = {52}, year = {2016}, month = {NOV}, pages = {14462-14465}, doi = {10.1039/C6CC08385D}, author = {Bagle, Pradip N. and Mane, Manoj V. and Vanka, Kumar and Shinde, Dinesh R. and Shaikh, Samir R. and Gonnade, Rajesh G. and Patil, Nitin T.} } @article {43797, title = {Intramolecular ipso-arylative cyclization of aryl-alkynoates and N-arylpropiolamides with aryldiazonium salts through merged gold/visible light photoredox catalysis}, journal = {Chemical Communications}, volume = {53}, year = {2017}, month = {AUG}, pages = {9081-9084}, type = {Article}, abstract = {A visible-light-promoted merged gold/photoredox catalyzed ipsoarylative cyclization has been reported. For instance, the reaction of aryl-alkynoates and N-arylpropiolamides with aryldiazonium salts in the presence of catalytic amounts of [(4-OCH3)C6H4](3)PAuCl and Ru(bpy)(3)(PF6)(2) under irradiation using a 32WCFL bulb gave arylated spirocarbocycles in moderate to good yields.}, doi = {10.1039/c7cc04010e}, author = {Bansode, Avinash H. and Shaikh, Samir R. and Gonnade, Rajesh G. and Patil, Nitin T.} } @article {45485, title = {Total synthesis and biological evaluation of cell adhesion inhibitors peribysin A and B: structural revision of peribysin B}, journal = {Organic letters }, volume = { 20}, year = {2018}, month = {NOV}, pages = {7003-7006}, type = {Article }, abstract = {Total synthesis of potent cell-adhesion inhibitors peribysins A and B has been accomplished for the first time in racemic form. A Diels-Alder/aldol sequence to build the skeleton and decoration of the desired functionalities of the targeted natural products using highly stereoselective operations are the highlights. The structures of synthesized peribysins were fully characterized using spectral data and single-crystal X-ray analysis. Through this total synthesis, the initially proposed structure of peribysin B has been revised. Furthermore, the cell-adhesion inhibition potential of the scaffold (two peribysins + three analogues) was confirmed using anti-adhesion assay.}, issn = {1523-7060}, doi = { 10.1021/acs.orglett.8b02838}, author = {Kalmode, Hanuman P. and Handore, Kishor L. and Rajput, Raveena and Shaikh, Samir R. and Gonnade, Rajesh G. and Kulkarni, Kiran A. and Reddy, D. Srinivasa} } @article {46344, title = {Crystal engineering for intramolecular pi-pi stacking: effect of sequential substitution of f on molecular geometry in conformationally flexible sulfonamides}, journal = {Crystal Growth \& Design}, volume = {19}, year = {2019}, month = {OCT}, pages = {5665-5678}, type = {Article}, abstract = {

A small library of ten sulfonamide derivatives comprising two aromatic rings was synthesized to investigate the effect of chronological positioning of the F-atom on the intramolecular pi-stacking assembly. The sequential positioning of F atoms was carried out on one of the aromatic rings that is linked to the sulfonamide moiety directly while the other aromatic ring (phenyl or pyridine) is linked by an ethyl spacer with the sulfonamide moiety. The ethyl spacer is provided to achieve the required flexibility so that both aromatic rings can bend to acquire syn conformation facilitated pi-stacking between electron-deficient and electron-rich aromatic rings. The idea was to study the interplay between hydrogen bonding and pi-stacking synthons in the conformationally flexible sulfonamide derivatives. The solid-state conformation of all the derivatives was investigated using the single-crystal X-ray diffraction technique. Crystal structure analysis revealed that the syn conformation was achieved only in trifluoro and pentafluoro sulfonamide derivatives with benzene substitution while in all other derivatives the molecules take either midway or anti conformations. None of the sulfonamide molecules with a pyridine moiety showed syn conformation. It could be because of the involvement of the pyridine N-atom in the hydrogen bonding dimeric synthon. The molecular conformation study in solution state using 2D NOESY and HOESY NMR experiments also substantiated syn conformation in a pentafluoro sulfonamide molecule with benzene substitution. The conformational analysis carried out employing density functional theory (DFT) calculations confirmed higher stability for the syn conformation over midway and anti orientations.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.9b00667}, author = {Shaikh, Samir R. and Gawade, Rupesh L. and Kumar, Deepak and Kotmale, Amol and Gonnade, Rajesh G. and Stuerzer, Tobias} } @article {46428, title = {Cyanuric-chloride-mediated synthesis of 2-Aryl-3-tert-butoxycarbonyl-thiazolidine-4-carboxylic acid anilides: mechanistic, X-ray crystal structures and cytotoxicity studies}, journal = {ChemistrySelect}, volume = {4}, year = {2019}, month = {NOV }, pages = {12534-12546}, type = {Article}, abstract = {

The {\textquoteleft}2R,4R{\textquoteright}-2-aryl thiazolidine-4-carboxylic acid anilides (ATCAAs) were synthesized using cyanuric chloride (CC) as a clean and substoichiometric acid-amine coupling agent under optimized reaction conditions. The diesterphenol intermediate based mechanism is proposed and supported by spectral characterization of the intermediate. The single crystal X-ray structures of acid substrate (2R,4R)-3-(tert-butoxycarbonyl)-2-(2-methoxyphenyl)thiazolidine-4-carbox ylic acid (3 a) and anilides (R)-tert-butyl 4-(2-fluorophenylcarbamoyl)thiazolidine-3-carboxylate (4 b), (2R,4R)-tert-butyl 2-(2,6-dichlorophenyl)-4-(m-tolylcarbamoyl)thiazolidine-3-carboxylate (6 b) confirmed the formation of chiral anilides. The synthesized library of anilides [(R)-tert-butyl 4-Aryl thiazolidine-3-carboxylate and (2R,4R)-tert-butyl 2-Aryl-4-Aryl thiazolidine-3-carboxylate] 4 a-6 f was screened for their in vitro anti cancer, neuronal and neuroprotective studies. The anilides 4 b, 4 g, 5 d, 5 h, 6 c and 6 f (where the aryl=2-fluorophenylcarbamoyl, 4-chlorophenylcarbamoyl, 2-methoxyphenyl, 2,5-dichlorophenylcarbamoyl, 2,6-dichlorophenyl, 4-chlorophenylcarbamoyl respectively)were found to be less cytotoxic towards N2 A, SHSY-5Y neuronal cell lines in their differentiated and undifferentiated forms, and also exhibited dose dependant anti-inflammatory properties for a possible identification towards neurodegenerative and inflammatory disorders.

}, keywords = {Acid-amine coupling, Cyanuric chloride, Cytotoxicity, Mechanistic investigations, Single crystal x-ray structure}, issn = {2365-6549}, doi = {10.1002/slct.201903000}, author = {Jagtap, Rohidas M. and Shaikh, Samir R. and Gonnade, Rajesh G. and Raheem, Shabnam and Rizvi, Masood A. and Pardeshi, Satish K.} } @article {46138, title = {Efficient broad-band emission from contorted purely corner-shared one dimensional (1D) organic lead halide perovskite}, journal = {Chemistry of Materials}, volume = {31}, year = {2019}, month = {APR }, pages = {2253-2257}, type = {Article}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.9b00069}, author = {Biswas, Anupam and Bakthavatsalam, Rangarajan and Shaikh, Samir R. and Shinde, Aparna and Lohar, Amruta and Jena, Satyam and Gonnade, Rajesh G. and Kundu, Janardan} } @article {45519, title = {Gold(I)-catalyzed hydroxy group assisted C(sp(2))-H alkylation of enaminones with diazo compounds to access 3-alkyl chromones}, journal = {Organic Letters}, volume = {21}, year = {2019}, month = {JAN }, pages = {335-339}, type = {Article}, abstract = {

A strategy for expedient synthesis of 3-substituted chromones from easily available o-hydroxyarylenaminones and diazo compounds has been developed. Carefully conducted experimental and computational studies led us to propose an uncommon mechanistic pathway involving the hydroxyl group assisted alkylation of enaminones with in situ generated gold carbenes.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.8b03989}, author = {Bagle, Pradip N. and Mane, Manoj V. and Sancheti, Shashank P. and Gade, Amol B. and Shaikh, Samir R. and Baik, Mu-Hyun and Patil, Nitin T.} } @article {46991, title = {Ligand structure directed dimensionality reduction (2D -> 1D) in lead bromide perovskite}, journal = {Journal of Physical Chemistry C}, volume = {124}, year = {2020}, month = {JAN}, pages = {1888-1897}, type = {Article}, abstract = {

Low dimensional (2D, 1D) lead halide perovskites are currently attracting huge research interest due to their enabling properties. Demonstrating synthetic control on the dimensionality/ structure of these perovskites is highly challenging. Dimensionality in these perovskites is largely dictated by the nature/structure and composition of the incorporating ligands and the utilized synthetic conditions. Here, we demonstrate chemical composition based control on reduction of dimensionality (2D -\> 1D) for lead bromide perovskite utilizing 2-(2-aminoethyl)isothiourea dihydrobromide as a common precursor ligand (Isothio Bromide). Controlling the hydrothermal reaction parameters (temperature, time) at a fixed precursor ratio affords corner-shared, contorted 2D sheet perovskite and corner-shared, contorted, chiral 1D chain perovskite. Such dimensionality reduction leads to contrasting photophysical properties: 1D chain perovskite shows long-lived and self-trapped broad band emission, whereas 2D perovskite shows short-lived, band edge emission with a long tail. Mechanistic studies and single crystal structure analysis reveal the incorporation of the utilized precursor ligand (Isothio Bromide) in 2D perovskite. Surprisingly, the 1D perovskite is found to be chiral (P2(1) space group) incorporating 2-(2-aminoethyldisulfanyl)ethanamine and ammonium ions as the achiral ligands generated in situ due to hydrothermal cleavage of the precursor (Isothio Bromide) ligand. Such structural and compositional change of the ligands, which manifests a different hydrogen bonding network in the resultant perovskite structure, plays a decisive role in dictating the final molecular formula and dimensionality/structure of the perovskite which largely controls their photophysical properties.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.9b11033}, author = {Bakthavatsalam, Rangarajan and Haris, Muhammed P. U. and Shaikh, Samir R. and Lohar, Amruta and Mohanty, Ashutosh and Moghe, Dhanashree and Sharma, Shivani and Biswas, Chinmoy and Raavi, Sai Santhosh Kumar and Gonnade, Rajesh G. and Kundu, Janardan} } @article {46864, title = {Synthesis and biological activity of imidazole based 1,4-naphthoquinones}, journal = {New Journal of Chemistry}, volume = {44}, year = {2020}, month = {MAY }, pages = {6889-6901}, type = {Article}, abstract = {

Design and development of drugs in multi-drug resistant (MDR) infections have been of growing interest. We report the syntheses, and antibacterial and antifungal activities of imidazole-based 1,4-naphthoquinones (I-1 to I-4; 1-alkyl-2-methyl-1H-naphtho[2,3-d]imidazole-4,9-dione (alkyl = methyl to butyl)) and their precursors (B-3; N-(3-chloro-1,-dioxo-1,4-dihydronaphthalen-2-yl)acetamide) and A-1 to A-4; N-(3-(alkylamino)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acetamide (alkyl = methyl to butyl). Crystal structures of B-3, A-1 to A-3 and I-2 to I-4 were obtained through single crystal X-ray diffraction experiments. Electronic structure and charge distribution have further been characterized with the use of Density Functional Theory. Seven of these derivatives display a broad spectrum of antibacterial activity against few selected bacterial strains (Gram-positive and Gram-negative). As demonstrated MIC values with B-2 and B-3 against bacterial isolates were 8-64 mu g ml(-1) and those against pathogenic yeast, C. albicans, were observed in the range of 128-256 mu g ml(-1). MIC data of these derivatives suggest them to be promising against pathogens.

}, issn = {1144-0546}, doi = {10.1039/c9nj04339j}, author = {Choudhari, Dinkar and Salunke-Gawali, Sunita and Chakravarty, Debamitra and Shaikh, Samir R. and Lande, Dipali N. and Gejji, Shridhar P. and Rao, Pradeep Kumar and Satpute, Surekha and Puranik, Vedavati G. and Gonnade, Rajesh} }