@article { ISI:000227930800016, title = {Efficient method for the synthesis of methyl 11 alpha-amino-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate}, journal = {Tetrahedron}, volume = {61}, number = {14}, year = {2005}, month = {APR}, pages = {3605-3612}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The synthesis of methyl 11 alpha-azido-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate, methyl 11 beta-azido-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate and methyl 11 alpha-amino-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate have been achieved. Mechanistic aspects for the decomposition of steroidal azidoketones to its enamines are discussed. (c) 2005 Elsevier Ltd. All rights reserved.

}, keywords = {11-aminosteroid, 11-azidosteroid, base catalyzed epimerization, HIV-1 protease inhibitors, steroidal enamines}, issn = {0040-4020}, doi = {10.1016/j.tet.2005.01.073}, author = {Salunke, D. B. and Hazra, Braja G. and Gonnade, Rajesh G. and Bhadbhade, Mohan M. and Pore, V. S.} } @article {Shanbhag, title = {Enantioselective syntheses of (-)-pinellic acid, alpha- and beta-dimorphecolic acid}, journal = {Tetrahedron}, volume = {63}, number = {32}, year = {2007}, month = {AUG}, pages = {7624-7633}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient enantioselective convergent approach for the synthesis of (-)-pinellic acid 1, alpha- and beta- dimorphecolic acid (2 and 3) from 1,9-nonane diol is described. The synthetic strategy features Sharpless asymmetric hydroxylation, Sonogashira coupling and Birch reduction. (C) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {asymmetric dihydroxylation, influenza, Sonogashira coupling}, issn = {0040-4020}, doi = {10.1016/j.tet.2007.05.047}, author = {Baruah, Pranjal K. and Gonnade, Rajesh G. and Sanjayan, Gangadhar J.} } @article {45}, title = {Enforcing periodic secondary structures in hybrid peptides: a novel hybrid foldamer containing periodic gamma-turn motifs}, journal = {Journal of Organic Chemistry}, volume = {72}, number = {2}, year = {2007}, month = {JAN}, pages = {636-639}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

{This note describes the design, synthesis, and conformational studies of a novel hybrid foldamer that adopts a definite compact, three-dimensional structure determined by a combined effect of the special conformational properties of the foldamer constituents. The striking feature of this de novo designed foldamer is its ability to display periodic gamma-turn conformations stabilized by intramolecular hydrogen bonds. Conformational investigations by single-crystal X-ray studies, solution-state NMR, and ab initio MO theory at the HF/6-31G*

}, keywords = {ammonia-TPD, benzylation reaction, Ce-Al-MCM-41, Friedel-Crafts alkylation, pyridine-FrIR}, issn = {0935-9648}, doi = {10.1021/jo062032w}, author = {Baruah, Pranjal K. and Sreedevi, N. K. and Gonnade, Rajesh G. and Ravindranathan, Sapna and Damodaran, Krishnan and Hofmann, Hans-Joerg and Sanjayan, Gangadhar J.} } @article { ISI:000251275500002, title = {Expeditious assembly of 3,4-benzannulated 8-oxabicyclo[3.2.1]octane systems by [2+2+2] alkyne cyclotrimerisation: Total synthesis of (-)-bruguierol A}, journal = {European Journal of Organic Chemistry}, number = {33}, year = {2007}, month = {NOV}, pages = {5483-5486}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

Facile construction of benzene-fused 8-oxabicyclo[3.2.1]octane systems by employing a cross alkyne cyclotrimerisation reaction was explored. With this procedure, (-)-bruguierol A was synthesised, and its absolute configuration was established.

}, keywords = {cyclotrimerisation, epoxidation, Total synthesis, Wilkinson{\textquoteright}s catalyst}, issn = {1434-193X}, doi = {10.1002/ejoc.200700648}, author = {Ramana, Chepuri V. and Salian, Sumanth R. and Gonnade, Rajesh G.} } @article { ISI:000257280500014, title = {Expeditious one-step entry to the tetracyclic core of integrastatins}, journal = {Chemical Communications}, number = {27}, year = {2008}, month = {MAY}, pages = {3151-3153}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Herein we describe a one-step assembly of structurally complex small molecules representing the central skeleton of integrastatins by employing a simple pinacol transform.

}, issn = {1359-7345}, doi = {10.1039/b801755g}, author = {Ramana, C. V. and Reddy, Challa Nageswara and Gonnade, Rajesh G.} } @article { ISI:000262301900031, title = {Enhancing intermolecular benzoyl-transfer reactivity in crystals by growing a {\textquoteleft}{\textquoteleft}reactive{\textquoteright}{\textquoteright} metastable polymorph by using a chiral additive}, journal = {Chemistry-A European Journal}, volume = {15}, number = {1}, year = {2009}, month = {NOV}, pages = {261-269}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

Racemic 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoacetate, which normally crystallizes in a monoclinic form (form I, space group P2(1)/n) could be persuaded to crystallize out as a metastable polymorph (form II, space group C2/c) by using a small amount of either D- or L- 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoformate as an additive in the crystallization medium. The structurally similar enantiomeric additive was chosen by the scrutiny of previous experimental results on the crystallization of racemic 2,4-di-O-benzoyl-myo-inositol-1,3,5-orthoacetate. Form II crystals call be thermally transformed to form I crystals at about 145 degrees C. The relative organization of the molecules in these dimorphs vary slightly in terms of the helical assembly of molecules, that is, electrophile (El)center dot center dot center dot nucleophile (Nu) and C-H center dot center dot center dot pi interactions, but these minor variations have a profound effect on the facility and specificity of benzoyl-group-transfer reactivity in the two crystal forms. While form II crystals undergo a clean intermolecular benzoyl-group-transfer reaction, form I crystals are less reactive and undergo non-specific benzoyl-group transfer leading to a Mixture of products. The role played by the additive in fine-tuning small changes that are required in the molecular packing opens up the possibility of creating new polymorphs that show varied physical and chemical properties. Crystals of D-2.6-di-O-benzoyl-myo-inositol-1,3,5-orthoformate (additive) did not show facile benzoyl-group-transfer reactivity (in contrast to the corresponding racemic compound) due to the lack of proper juxtaposition and assembly of molecules.

}, keywords = {Acylation, carbohydrates, Crystal growth, cyclitols, solid-state reactions}, issn = {0947-6539}, doi = {10.1002/chem.200801484}, author = {Murali, Chebrolu and Shashidhar, Mysore S. and Gonnade, Rajesh G. and Bhadbhade, Mohan M.} } @article { ISI:000264236700037, title = {Exploration of click reaction for the synthesis of modified nucleosides as chitin synthase inhibitors}, journal = {Bioorganic \& Medicinal Chemistry}, volume = {17}, number = {6}, year = {2009}, month = {MAR}, pages = {2433-2440}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Click reaction approach toward the synthesis of two sets of novel 1,2,3-triazolyl linked uridine derivatives 19a-19g and 21a-21g was achieved by Cu(I)-catalyzed 1,3-dipolar cycloaddition of 5{\textquoteright}-azido-5{\textquoteright}-deoxy-2{\textquoteright},3{\textquoteright}-O-(1-methylethylidene) uridine (17) with propargylated ether of phenols 18a-18g and propargylated esters 20a-20g. Structure of one of the representative compound 19d was unambiguously confirmed by X-ray crystallography. Chitin synthase inhibition study of all these compounds 19a-19g and 21a-21g was carried out to develop antifungal strategy. Compounds 19d, 19e, 19f, and 21f were identified as potent chitin synthase inhibitors by comparing with nikkomycin. Compounds 19a, 19b, 19c, 19d, 21a, and 21b showed good antifungal activity against human and plant pathogens. Compounds 19a, 19b, 19f, 21c, 21f, and 21g were identified as lead chitin synthase inhibitors for further modi. cations by comparing results of inhibition of growth, \% germ tube formation and chitin synthase activity. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {1, 2, 3-dipolar cycloaddition, 3-Triazole, 4-Disubstituted-1, 5 {\textquoteleft}-Azidouridine, Antifungal compounds, Chitin synthase activity, Click reaction, Uridine nucleosides}, issn = {0968-0896}, doi = {10.1016/j.bmc.2009.02.019}, author = {Chaudhary, Preeti M. and Chavan, Sayalee R. and Shirazi, Fazal and Razdan, Meenakshi and Nimkar, Prachi and Maybhate, Shailaja P. and Likhite, Anjali P. and Gonnade, Rajesh G. and Hazra, Braja G. and Deshpande, Mukund V. and Deshpande, Sunita R.} } @article { ISI:000328182900006, title = {Ester vs. amide on folding: a case study with a 2-residue synthetic peptide}, journal = {Organic \& Biomolecular Chemistry}, volume = {11}, number = {48}, year = {2013}, month = {DEC}, pages = {8348-8356}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Although known for their inferiority as hydrogen-bonding acceptors when compared to amides, esters are often found at the C-terminus of peptides and synthetic oligomers (foldamers), presumably due to the synthetic readiness with which they are obtained using protected peptide coupling, deploying amino acid esters at the C-terminus. When the H-bonding interactions deviate from regularity at the termini, peptide chains tend to {\textquoteleft}{\textquoteleft}fray apart{\textquoteright}{\textquoteright}. However, the individual contributions of C-terminal esters in causing peptide chain end-fraying goes often unnoticed, particularly due to diverse competing effects emanating from large peptide chains. Herein, we describe a striking case of a comparison of the individual contributions of C-terminal ester vs. amide carbonyl as a H-bonding acceptor in the folding of a peptide. A simple two-residue peptide fold has been used as a testing case to demonstrate that amide carbonyl is far superior to ester carbonyl in promoting peptide folding, alienating end-fraying. This finding would have a bearing on the fundamental understanding of the individual contributions of stabilizing/destabilizing non-covalent interactions in peptide folding.

}, issn = {1477-0520}, doi = {10.1039/c3ob41967c}, author = {Vijayadas, Kuruppanthara N. and Nair, Roshna V. and Gawade, Rupesh L. and Kotmale, Amol S. and Prabhakaran, Panchami and Gonnade, Rajesh G. and Puranik, Vedavati G. and Rajamohanan, Pattuparambil R. and Sanjayan, Gangadhar J.} } @article {42806, title = {Evaluation of viability of halogen{\textbullet}{\textbullet}{\textbullet}O2N interactions: insight form crystal packing in a series of isomeric halo and nitro substituted triaryl compounds with modular positioning of halogen and NO2 groups}, journal = {CrystEngComm}, volume = {15}, year = {2013}, month = {APR}, pages = {5283-5300}, abstract = {

A series of isomeric triaryl compounds with a modular positioning of the halogen and NO2 groups have been synthesized by the azide{\textendash}alkyne {\textquotedblleft}click reaction{\textquotedblright} and have been characterized by single crystal X-ray structure analysis. This isomeric series has provided an opportunity for understanding the efficiency of the bifurcated halogen...NO2 synthon in the organization of the molecules in the crystalline lattice. The changes in molecular conformation, crystal packing and supramolecular aggregation due to the change in the relative positioning of the complementary groups, halogen atom and the NO2 group on ring A and ring C respectively, have been discussed. All the isomers synthesized are crystalline and establish the triazole as a reliable linker for crystal engineering oriented molecular synthesis. The 2-NO2 derivatives display in general, a helical architecture and 3-NO2 derivatives exhibit a centrosymmetric dimeric assembly via the complementary C{\textendash}H...O interactions leading to either a helical or a 2-dimensional sheet pattern. The molecular organization in 4-NO2 derivatives revealed in general a 2D sheet pattern.

}, doi = {10.1039/C3CE40192H}, author = {Ramana, Chepuri V. and Goriya, Yogesh and Durugkar, Kulbhushan A. and Chatterjee, Soumitra and Krishnaswamy, Shobhana and Gonnade, Rajesh G.} } @article { ISI:000331163900009, title = {Efficient synthesis of 9-aryldihydrophenanthrenes by a cascade reaction involving arynes and styrenes}, journal = {Organic Letters}, volume = {16}, number = {3}, year = {2014}, month = {FEB}, pages = {676-679}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A mild, general, and transition-metal-free protocol for the synthesis of 9,10-dihydrophenanthrenes is reported. The aryne generated by the fluoride-induced,1,2-elimination of 2-(trimethylsilyl)aryl triflates undergoes an efficient cascade reaction initiated by the Diels-Alder reaction with the differently substituted styrenes leading to the formation of 9-aryl-9,10-dihydrophenanthrene derivatives in moderate to good yields.

}, issn = {1523-7060}, doi = {10.1021/ol4033094}, author = {Bhojgude, Sachin Suresh and Bhunia, Anup and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article { ISI:000359393500052, title = {Enantiospecific synthesis of both enantiomers of the longtailed mealybug pheromone and their evaluation in a new zealand vineyard}, journal = {Journal of Organic Chemistry}, volume = {80}, number = {15}, year = {2015}, month = {AUG}, pages = {7785-7789}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The irregular monoterpenoid sex pheromone of Pseudococcus longispinus and its enantiomer were prepared from the corresponding bornyl acetates. The use of readily accessible chiral starting materials and lactone lactone rearrangement are the highlights of the present synthesis. The biological activities of the two enantiomers and racemic mixture were tested in a New Zealand vineyard. The (S)-(+)-enantiomer was significantly more attractive to P. longispinus males than the racemic mixture or the (R)-(-)-enantiomer.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.5b01131}, author = {Ramesh, Remya and Bell, Vaughn and Twidle, Andrew M. and Gonnade, Rajesh G. and Reddy, D. Srinivasa} } @article { ISI:000368065300033, title = {Enantioselective synthesis of spirocyclohexadienones by NHC-catalyzed formal [3+3] annulation reaction of enals}, journal = {Angewandte Chemie-International Edition}, volume = {55}, number = {1}, year = {2016}, month = {JAN}, pages = {268-272}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

The enantioselective synthesis of pyrazolone-fused spirocyclohexadienones was demonstrated by the reaction of alpha,beta-unsaturated aldehydes with alpha-arylidene pyrazolinones under oxidative N-heterocyclic carbene (NHC) catalysis. This atom-economic and formal [3+3] annulation reaction proceeds through a vinylogous Michael addition/spiroannulation/dehydrogenation cascade to afford spirocyclic compounds with an all-carbon quaternary stereocenter in moderate to good yields and excellent ee values. Key to the success of the reaction is the cooperative NHC-catalyzed generation of chiral alpha,beta-unsaturated acyl azoliums from enals, and base-mediated tandem generation of dienolate/enolate intermediates from pyrazolinones.

}, keywords = {annulation reactions, asymmetric catalysis, N-heterocyclic carbenes, organocatalysis, spiro compounds}, issn = {1433-7851}, doi = {10.1002/anie.201507802}, author = {Yetra, Santhivardhana Reddy and Mondal, Santigopal and Mukherjee, Subrata and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {43441, title = {Engineering crystals that facilitate the acyl-transfer reaction: insight from a comparison of the crystal structures of myo-inositol-1,3,5-orthoformate-derived benzoates and carbonates}, journal = {ACTA Crystallographica Section C-Structural Chemistry}, volume = {72}, year = {2016}, month = {NOV}, pages = {875-+}, abstract = {Minor variations in the molecular structure of constituent molecules of reactive crystals often yield crystals with significantly different properties due to altered modes of molecular association in the solid state. Hence, these studies could provide a better understanding of the complex chemical processes occurring in the crystalline state. However, reactions that proceed efficiently in molecular crystals are only a small fraction of the reactions that are known to proceed (with comparable efficiency) in the solution state. Hence, for consistent progress in this area of research, investigation of newer reactive molecular crystals which support different kinds of reactions and their related systems is essential. The crystal structures and acyl-transfer reactivity of a myo-inositol-1,3,5-orthoformate-derived dibenzoate and its carbonate (4-O-benzoyl-2-O-phenoxycarbonyl-myo-inositol 1,3,5-orthoformate, C21H18O9) and thiocarbonate (4-O-benzoyl-2-O-phenoxythiocarbonyl-myo-inositol 1,3,5-orthoformate, C21H18O8S) analogs are compared with the aim of understanding the relationship between crystal structure and acyl-transfer reactivity. Insertion of an O atom in the acyl (or thioacyl) group of an ester gives the corresponding carbonate (or thiocarbonate). This seemingly minor change in molecular structure results in a considerable change in the packing of the molecules in the crystals of myoinositol-1,3,5-orthoformate-derived benzoates and the corresponding carbonates. These differences result in a lack of intermolecular acyl-transfer reactivity in crystals of myo-inositol-1,3,5-orthoformate-derived carbonates. Hence, this study illustrates the sensitivity of the relative orientation of molecules, their packing and ensuing changes in the reactivity of resulting crystals to minor changes in molecular structure.}, doi = {10.1107/S205322961601603X}, author = {Tamboli, Majid I. and Krishanaswamy, Shobhana and Gonnade, Rajesh G. and Shashidhar, Mysore S.} } @article { ISI:000378508900020, title = {Experimental and computational analysis of supramolecular motifs involving C-sp2(aromatic)-F and CF3 groups in organic solids}, journal = {New Journal of Chemistry}, volume = {40}, number = {6}, year = {2016}, month = {JUN}, pages = {4981-5001}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A detailed experimental (SCXRD) and theoretical (PIXEL and QTAIM) investigation of the evolution of different supramolecular motifs formed via the presence of both C(sp(2))/(sp(3))-F groups in the crystal packing has been performed in a series of newly synthesized substituted benzanilides (containing {\textquoteleft}{\textquoteleft}both{\textquoteright}{\textquoteright} the fluorine and the trifluoromethyl group in the same molecule) along with previously reported similarly related crystal structures [CrystEngComm, 2008, 10, 54-67; CrystEngComm, 2012, 14, 1972-1989, CrystEngComm, 2013, 15, 3711-3733]. It was observed that the highest stabilized molecular motifs primarily consist of C(sp(2))-H center dot center dot center dot F-C(sp(2)) H-bonds in preference to C(sp(2))-H center dot center dot center dot F-C(sp(3)) H-bonds in the crystal. The motifs involving C(sp(2))-H center dot center dot center dot F-C(sp(2))/(sp(3)) H bonds were observed to be present over the entire distance range between 2.2 and 2.7 angstrom, albeit the difference in energies of stabilization involving fluorine atoms attached to sp(2) and sp(3) carbon is not significant in molecular crystals. From QTAIM analysis, the C(sp(2))/(sp(3))-F center dot center dot center dot F-C(sp(2))/(sp(3)) interactions were observed to be a closed shell in nature and provide local stabilization, indicating the formation of bonds, similar to weak hydrogen bonds observed in crystals.

}, issn = {1144-0546}, doi = {10.1039/c5nj03211c}, author = {Panini, Piyush and Gonnade, Rajesh G. and Chopra, Deepak} } @article {43910, title = {Enantioselective synthesis of functionalized β-lactones by NHC-catalyzed aldol lactonization of ketoacids}, journal = {Journal of Organic Chemistry}, volume = {82}, year = {2017}, month = {AUG}, type = {Article}, abstract = {N-Heterocyclic carbene (NHC)-catalyzed intramolecular aldol lactonization of readily available ketoacids leading to the enantioselective synthesis of cyclopentane-fused β-lactones is presented. The reaction proceeds via the generation of NHC-bound enolate intermediates formed from the ketoacids in the presence of the peptide coupling reagent HATU and NHC generated from the chiral triazolium salt. The functionalized β-lactones are formed under mild conditions in high yields and enantioselectivities.}, doi = {10.1021/acs.joc.7b01526}, author = {Mondal, Santigopal and Mukherjee, Subrata and Das, Tamal Kanti and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {45713, title = {Engineering molecular topology: A pseudopeptidic macrocyclic figure-eight motif}, journal = {European Journal of Organic Chemistry}, year = {2017}, month = {FEB }, pages = {1120-1124}, type = {Article}, abstract = {

We herein present a rational-design strategy for the synthesis of molecules with figure-eight topology. The design concept is based on the incorporation of turn units in the back-bone of the macrocycle. The molecular structures and the folding are studied by X-ray crystallography and NMR, FT-IR, and CD spectroscopy.

}, keywords = {Macrocycles, noncovalent interactions, Pi interactions, topology, X-ray diffraction}, issn = {1434-193X}, doi = {10.1002/ejoc.201601365}, author = {Sharma, Sakshi and Thorat, Shridhar H. and Gonnade, Rajesh G. and Jasinski, Jerry P. and Butcher, Ray and Haridas, V.} } @article {44459, title = {Effect of crystal packing on the thermosalient effect of the pincer-type diester naphthalene-2,3-diyl-bis(4-fluorobenzoate): a new class II thermosalient solid}, journal = {Chemistry-A European Journal}, volume = {24}, year = {2018}, month = {MAR}, pages = {4133-4139}, abstract = {The pincer-like double ester naphthalene-2,3-diyl-bis(4-fluorobenzoate) (2) is pentamorphic. Upon heating crystals of form I to below their melting point (441-443 K), they undergo a phase transition accompanied by a thermosalient effect, that is, rare and visually striking motility whereby the crystals jump or disintegrate. The phase transition and the thermosalient effect are reversible. Analysis of the crystal structure revealed that form I is a class II thermosalient solid. Crystals of form III also underwent a reversible phase transition in the temperature range of 160 to 170 K; however, they were not thermosalient. Comparison of the structures and the mechanical responses of the two polymorphs revealed that the thermosalient effect of form I was due to reversible closing and opening of the arms of the diester molecules in a tweezer-like action.}, doi = {10.1002/chem.201705586}, author = {Tamboli, Majid I. and Karothu, Durga Prasad and Shashidhar, Mysore S. and Gonnade, Rajesh G. and Naumov, Pance} } @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 {46435, title = {Enantioselective formal total synthesis of (-)-quinagolide}, journal = {Organic Letters}, volume = {21}, year = {2019}, month = {NOV}, pages = {9089-9093}, type = {Article}, abstract = {

The enantioselective formal total synthesis of (-)-quinagolide has been accomplished in a linear sequence of 8 purification steps from pyridine. The key steps are (a) organocatalyzed Diets-Alder reaction for fixing all three stereocenters on piperidine ring; (b) protecting group enabled deoxygenation of isoquinuclidine skeleton under Birch reduction condition; (c) Lewis acid (TiCl4) catalyzed intramolecular Friedel-Crafts cyclization of dicarboxylic acid; and (d) one-pot diastereoselective ketone reduction-intramolecular cyclization to form oxazolidinone which enables trans-geometry installation. During the course of the synthesis, an interesting reductive cleavage of the C-N bond in the electron-deficient isoquinuclidine skeleton under the Birch reduction conditions has been observed. This is the first synthetic effort to access the core skeleton of (-)-quinagolide.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.9b03477}, author = {Chavan, Subhash P. and Kadam, Appasaheb L. and Gonnade, Rajesh G.} } @article {47159, title = {Experimental and theoretical charge density, intermolecular interactions and electrostatic properties of metronidazole}, journal = {Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials}, volume = {75}, year = {2019}, month = {DEC}, pages = {942-953}, type = {Article}, abstract = {

Metronidazole is a radiosensitizer; it crystallizes in the monoclinic system with space group P2(1)/c. The crystal structure of metronidazole has been determined from high-resolution X-ray diffraction measurements at 90 K with a resolution of (sin 0/lambda) max = 1.12 angstrom(-1). To understand the charge-density distribution and the electrostatic properties of metronidazole, a multipole model refinement was carried out using the Hansen-Coppens multipole formalism. The topological analysis of the electron density of metronidazole was performed using Bader{\textquoteright}s quantum theory of atoms in molecules to determine the electron density and the Laplacian of the electron density at the bond critical point of the molecule. The experimental results have been compared with the corresponding periodic theoretical calculation performed at the B3LYP/6-31G** level using CRYSTAL09. The topological analysis reveals that the N-O and C-NO2 exhibit less electron density as well as negative Laplacian of electron density. The molecular packing of crystal is stabilized by weak and strong inter- and intramolecular hydrogen bonding and H center dot center dot center dot H interactions. The topological analysis of O-H center dot center dot center dot N, C-H center dot center dot center dot O and H center dot center dot center dot H intra- and intermolecular interactions was also carried out. The electrostatic potential of metronidazole, calculated from the experiment, predicts the possible electrophilic and nucleophilic sites of the molecule; notably, the hydroxyl and the nitro groups exhibit large electronegative regions. The results have been compared with the corresponding theoretical results.

}, keywords = {atomic valence index, Electron density, Electrostatic potential, intermolecular interactions, metronidazole, radiosensitizer}, doi = {10.1107/S2052520619011272}, author = {Kalaiarasi, Chinnasamy and George, Christy and Gonnade, Rajesh G. and Hathwar, Venkatesha R. and Poomani, Kumaradhas} } @article {46643, title = {Effect of substituent of roof shape amines on the molecular recognition of optically active acids by NMR spectroscopy}, journal = {ChemistrySelect}, volume = {5}, year = {2020}, month = {NOV}, pages = {13183-13190}, type = {Article}, abstract = {

Optically active roof shape derivatives of benzyl amines were synthesized and screened as chiral solvating agents for the study of molecular recognition of chiral compounds by NMR and UV spectroscopy. The effect of substituents on the aromatic ring of benzyl unit is investigated to assess the binding ability with the analyte and an experimental correlation is observed. Altering the substituents on the ring of benzyl amine and the acidic substrates, significantly influence the CSA interactions. The supramolecular interactions between acid and amine in the single crystal X-ray analysis of the diastereomeric salts provide further insight of the mode of molecular recognition.

}, keywords = {Chiral Solvating Agents, molecular recognition, NMR spectroscopy, Roof Shape Amine, UV spectroscopy}, issn = {2365-6549}, doi = {10.1002/slct.202003338}, author = {Gupta, Riddhi and Gonnade, Rajesh G. and Bedekar, Ashutosh V.} } @article {46782, title = {Enantioselective synthesis of tricyclic beta-lactones by NHC-catalyzed desymmetrization of cyclic 1,3-diketones}, journal = {Organic Letters}, volume = {22}, year = {2020}, month = {JUL}, pages = {5407-5411}, type = {Article}, abstract = {

The NHC-catalyzed desymmetrization of cyclic-1,3-diketones allowing the enantioselective construction of tricyclic beta-lactones with five contiguous stereocenters, including two quaternary stereocenters, has been developed. The mild and operationally simple addition of a-bromoenals to cyclopentane-1,3-diketone derivatives proceeds via the initial formation of chiral alpha,beta-unsaturated acylazolium intermediates and culminates in a cascade reaction, following the Michael-aldol-Iactonization pathway to deliver the beta-lactone derivatives in moderate to good yields and excellent selectivity.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.0c01756}, author = {Shee, Sayan and Mukherjee, Subrata and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {47626, title = {Enantioselective synthesis of 5,6-dihydroindolizines by N-heterocyclic carbene (NHC)-catalyzed core-structure-inspired strategy of azolium-enolate cascade}, journal = {Organic Letters}, volume = {23}, year = {2021}, month = {JUL }, pages = {5223-5228}, type = {Article}, abstract = {The core-structure motivated design has allowed the enantioselective synthesis of 5,6-dihydroindolizines via N-heterocyclic carbene (NHC) catalysis. The NHC-catalyzed reaction of alpha,beta-unsaturated aldehydes with the suitably substituted pyrrole derivatives proceed via the initial generation of alpha,beta-unsaturated acylazoliums from enals, and enolates from pyrroles and the reaction culminated in an efficient cascade process involving the Michael-aldol-lactonization-decarboxylation sequence to afford the products in reasonable yields and high selectivities. The method is further extended to the construction of spirocyclic 5,6-dihydroindolizines.}, issn = {1523-7060}, doi = {10.1021/acs.orglett.1c01761}, author = {Ghosh, Arghya and Shee, Sayan and Barik, Shilpa and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {48083, title = {Efficient route to 3,3 {\textquoteleft}-biindolinylidene-diones by iron-catalyzed dimerization of isatins}, journal = {Chemistry-an Asian Journal}, volume = {17}, year = {2022}, month = {AUG}, pages = {e202200414}, type = {Article}, abstract = {

Iron-catalyzed dimerization of various isatin derivatives is described for the efficient synthesis of 3,3 {\textquoteleft}-biindolinylidene-diones (isoindigos). The reaction provides easy access to self-coupled and cross-coupled 3,3 {\textquoteleft}-indolinylidene-diones that have high relevance to biology and materials. This Fe(0)- or Fe(II)-catalyzed dimerization reaction tolerates a wide range of functionalities, such as fluoro, chloro, bromo, alkenyl, nitrile, ether, ester, pyrrolyl, indolyl and carbazolyl groups, including cyclic and acyclic alkyls as well as an alkyl-bearing fatty-alcohol moiety. Especially, the coupling between two distinct isatins provided excellent selectivity for the cross-dimerization with trace of self-couplings. The single-crystal X-ray diffraction study established the molecular structure of eight dimerized products. A preliminary mechanistic study of the Fe-catalyzed dimerization supported the radical pathway for the reaction.

}, keywords = {Cross-coupling, dimerization, iron, Isatin, Isoindigo, Mechanism}, issn = {1861-4728}, doi = {10.1002/asia.202200414}, author = {Jagtap, Rahul A. and Pradhan, Chandini and Gonnade, Rajesh G. and Punji, Benudhar} } @article {48358, title = {Enantioselective synthesis of dihydrothiopyranones via NHC- catalyzed [3+3] annulation of 2-bromoenals with beta-oxodithioesters}, journal = {Organic Letters}, volume = {24}, year = {2022}, month = {DEC}, pages = {8848-8853}, type = {Article}, abstract = {

The N-heterocyclic carbene (NHC)-organocata-lyzed [3 + 3] annulation of 2-bromoenals with fi-oxodithioesters resulting in the enantioselective synthesis of dihydrothiopyranones is presented. The chiral a,fi-unsaturated acylazoliums generated from 2-bromoenals and carbenes underwent smooth interception with the sulfur nucleophiles to furnish the sulfur heterocycles in satisfactory yields/selectivity. The regioselective formation of dihydrothiopyranones over the competing dihydropyranones is noteworthy.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.2c03642}, author = {Barik, Shilpa and Shee, Sayan and Gonnade, Rajesh G. and Biju, Akkattu T.} }