@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:000306670200022, title = {InCl3-mediated addition of indole to isatogens: an expeditious synthesis of 13-deoxy-isatisine A}, journal = {Chemistry-A European Journal}, volume = {18}, number = {31}, year = {2012}, month = {JUL}, pages = {9601-9611}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A strategy directed towards the total synthesis of isatisine A that involves several late-stage metal-catalyzed transformations that address the key carboncarbon and carbonheteroatom bond formations has been developed. As a part of this strategy, methods for the addition of indoles to isatogens that lead selectively to either 2,2-disubstituted N-hydroxyindolin-3-one or 2,2-disubstituted indolin-3-one compounds have been developed by employing InCl3 as a catalyst or as the reagent. The present methods provide the first examples of the additions of indoles to the isatogen nucleus. To demonstrate its viability, the synthesis of 13-deoxy-isatisine A has been completed in ten steps from a known and easily available lactone.

}, keywords = {indium, indoles, isatogens, Natural products, Total synthesis}, issn = {0947-6539}, doi = {10.1002/chem.201103604}, author = {Kumar, Chepuri V. Suneel and Puranik, Vedavati G. and Ramana, Chepuri V.} } @article {50207, title = {Ru(II)-catalyzed C3-H functionalization of indoles with isatogens}, journal = {Advanced Synthesis \& Catalysis}, volume = {368}, year = {2026}, month = {JUL}, pages = {e70625}, type = {Article}, abstract = {

A simple methodology for the synthesis of the 2-(1H-indol-3-yl)indolin-3-one core present in various natural products is developed. This method comprises Ru(II)-catalyzed regioselective addition of indole to isatogen, along with N \& horbar;O bond reduction. A range of indolin-3-one compounds incorporating a C2-indolyl unit are synthesized under catalytic conditions in good yields, including the natural products halichrome A and metagenediindole A. With the help of control experiments and density functional theory calculations, a plausible mechanism founded upon the involvement of a bimetallic Ru complex is proposed.

}, keywords = {2-(1H-indol-3-yl)indolin-3-one, indoles, isatogens, N \& horbar, O bond reduction, pseudoindoxyl natural products}, issn = {1615-4150}, doi = {10.1002/adsc.70625}, author = {Hegde, Chaitra Narayan and Rajeshkumar, Thayalan and Maron, Laurent and Ramana, Chepuri V.} }