@article { ISI:000284515800005, title = {Combined experimental and density functional theory study on the Pd-mediated cycloisomerization of o-alkynylnitrobenzenes - synthesis of isatogens and their evaluation as modulators of ROS-mediated cell death}, journal = {European Journal of Organic Chemistry}, number = {31}, year = {2010}, month = {NOV}, pages = {5955-5966}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

Highly selective cycloisomerization of o-alkynylnitrobenzenes, leading to isatogens, has been achieved by employment of a Pd-II complex. This reaction is very general and functional-group-tolerant. The possible mechanism of this reaction was investigated with the help of DFT calculations. Three possible pathways - namely, the addition of the nitro group either in (i) 5-exo-dig or (ii) 6-endo-dig mode and (iii) halopalladation - and subsequent intramolecular events have been considered and studied in detail. These investigations revealed that pathway (i) is the favored route to isatogen formation. A preliminary screening of the available isatogens reveals the 2-alkylisatogens to be novel ROS scavengers capable of inhibiting cellular necroptosis.

}, keywords = {Anthranil, cyclization, Density functional calculations, isatogens, Nitro-alkyne cycloisomerization, Palladium}, issn = {1434-193X}, doi = {10.1002/ejoc.201000769}, author = {Ramana, Chepuri V. and Patel, Pitambar and Vanka, Kumar and Miao, Benchun and Degterev, Alexei} } @article { ISI:000295890100012, title = {Divergent Pd(II) and Au(III) mediated nitroalkynol cycloisomerizations}, journal = {Organic \& Biomolecular Chemistry}, volume = {9}, number = {21}, year = {2011}, month = {JUN}, pages = {7327-7334}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A new cycloisomerization reaction comprising the simultaneous addition of nitro and alcohol groups across C C leading to skeletally diverse small molecules is documented.

}, issn = {1477-0520}, doi = {10.1039/c0ob00858c}, author = {Patel, Pitambar and Ramana, Chepuri V.} } @article { ISI:000311926100005, title = {Total synthesis of (-)-isatisine A}, journal = {Journal of Organic Chemistry}, volume = {77}, number = {23}, year = {2012}, month = {DEC}, pages = {10509-10515}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A modular total synthesis of (-)-isatisine A is described in which four consecutive metal-mediated transformations have been employed at the final stage. These include [Pd]-catalyzed Sonogashira coupling, [Pd]-catalyzed nitroalkyne cycloisomerization leading to isatogens, and addition of indoles to isatogens using InCl3- and [Rh]-catalyzed oxidative N-heterocyclization of amino alcohol to form the key amide bond. In addition to these, the removal of the protecting groups has also been carried out in a selective fashion employing either catalytic or stoichiometric metal/metal-based reagents.

}, issn = {0022-3263}, doi = {10.1021/jo302198v}, author = {Patel, Pitambar and Ramana, C. V.} } @article { ISI:000330816000048, title = {Synthesis of the central tricyclic core of the isatisine A: harmonious orchestration of [metal]-catalyzed reactions in a sequence}, journal = {Tetrahedron}, volume = {70}, number = {2}, year = {2014}, month = {JAN}, pages = {510-516}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Two sequential metal-catalyzed transformations, involving [In]-catalyzed Friedel Crafts type addition of spiroaminol carbon to indole C3 followed by [Rh]-catalyzed dehydrogenative cyclization of the resulting gamma-amino alcohol culminated in the construction of the central tricyclic core isatisine A. The overall strategy employed three easily available starting compounds and delivered the complex tricyclic core in four steps with all four steps being catalytic in nature. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Dehydrogenative cyclization, Friedel-Crafts reaction, Indium chloride, Isatisine A, Rhodium, Spiro-3-indolinone}, issn = {0040-4020}, doi = {10.1016/j.tet.2013.11.026}, author = {Patel, Pitambar and Reddy, B. Narendraprasad and Ramana, C. V.} } @article { ISI:000378303400010, title = {Ir(III)-catalyzed carbenoid functionalization of benzamides: synthesis of N-methoxyisoquinolinediones and N-methoxyisoquinolinones}, journal = {Organic Letters}, volume = {18}, number = {12}, year = {2016}, month = {JUN}, pages = {2828-2831}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A mild and efficient Ir(III)-catalyzed C-H carbenoid functionalization strategy has been developed to access. N-methoxyisoquinolinediones and N-methoxyisoquinolinones. The reaction proceeds efficiently in high yield at room temperature over a broad range of substrates without requirement of any additional oxidants or a base.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.6b01072}, author = {Phatake, Ravindra S. and Patel, Pitambar and Ramana, Chepuri V.} } @article { ISI:000368563200037, title = {Ir(III)-catalyzed synthesis of isoquinoline N-oxides from aryloxime and alpha-diazocarbonyl compounds}, journal = {Organic Letters}, volume = {18}, number = {2}, year = {2016}, month = {JAN}, pages = {292-295}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

An efficient Ir(III)-catalyzed C-H activation and annulations of aryloxime with a-diazocarbonyl compounds has been developed for the synthesis of substituted isoquinoline N-oxides. The reaction proceeds under mild atmospheric conditions, without any external oxidants and releases N-2 and H2O as the byproducts. In addition, synthetic applications of the N-oxide products have been established by performing further functionalization. An interesting dimeric iridacyclic complex allied through a bis-silver carboxylate bridge has been isolated that efficiently catalyzed the reaction.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.5b03462}, author = {Phatake, Ravindra S. and Patel, Pitambar and Ramana, Chepuri V.} } @article {47658, title = {Synthesis of anisotropic rod-like gold nanostructures in organic media}, journal = {Journal of Chemical Sciences}, volume = {133}, year = {2021}, month = {DEC}, pages = {106}, type = {Article}, abstract = {Synthesis of anisotropic rod-like gold nanostructures was carried out in chloroform employing a modified ascorbic acid derivative as a reducing agent in the presence and absence of seed particles. The seed particles and/or the chloroaurate ions were phase transferred to the organic media using n-octadecyl amine. High-resolution transmission electron microscopy analysis clearly revealed that the anisotropic structures are single crystalline in nature. The stabilization of certain crystallographic faces of anisotropic gold nanostructures by amines is invoked to explain the formation of these structures.}, issn = {0974-3626}, doi = {10.1007/s12039-021-01952-z}, author = {Prasad, V, Bhagavatula L. and Sivasankaran, Prathap Chandran and Patel, Pitambar and Malekar, V, Pushpa and Maya, V, K. and Ramana, V, Chepuri} } @article {47657, title = {Synthesis of anisotropic rod-like gold nanostructures in organic media (vol 133, 106, 2021)}, journal = {Journal of Chemical Sciences}, volume = {133}, year = {2021}, month = {DEC}, pages = {120}, type = {Correction}, issn = {0974-3626}, doi = {10.1007/s12039-021-01992-5}, author = {Prasad, V. Bhagavatula L. and Sivasankaran, Prathap Chandran and Patel, Pitambar and Malekar, V. Pushpa and Maya, V. K. and Ramana, V. Chepuri} } @article {47705, title = {Total synthesis of the pseudoindoxyl class of natural products}, journal = {Organic \& Biomolecular Chemistry}, volume = {19}, year = {2021}, month = {OCT}, pages = {7970-7994}, type = {Review}, abstract = {The pseudoindoxyl sub-structural motif, amongst the large set of the indole class of alkaloids, represents a unique subset of the oxygenated indole class of the alkaloid family. A majority of this class of natural products contains complex bridged/polycyclic scaffolds with interesting biological profiles. They are thus attractive synthetic targets. Starting from 1963, twenty-eight natural products having the pseudoindoxyl scaffold have been isolated, among which the synthesis of 13 natural products has been accomplished. In this review, we highlight the completed as well as the formal total synthesis of the natural products with a spiro-pseudoindoxyl ring, with a focus on their development. The challenges and the future perspective based on the recent developments in the field will also be discussed. We strongly believe that this review will not only update but also attract the attention of researchers in dealing with the synthesis of pseudoindoxyl compounds.}, issn = {1477-0520}, doi = {10.1039/d1ob01285a}, author = {Dhote, Pawan S. and Patel, Pitambar and Vanka, Kumar and Ramana, Chepuri V.} }