@article {42817, title = {Steric control in pd-mediated cycloisomerization of sugar alkynols: documentation of a rare allylic epimerization}, journal = {Tetrahedron Letters}, volume = {48}, year = {2007}, month = {JUL}, pages = {4771-4774}, type = {Article}, abstract = {

Pd-mediated cycloisomerization of C3-alkynylated glucofuranosyl derivatives revealed a dominance of steric factors over electronic factors. However, the intermediate glycals were epimerized prior to the ketalization and afforded the more stable cis-fused bicyclic ketals. (c) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {Bis-Homopropargylic Alcohols; Oriented Organic-Synthesis;Nucleophilic-Attack; Room-Temperature; Palladium; Chemistry; Heterocycles;Complexes; Transformations; Sonogashira}, doi = {10.1016/j.tetlet.2007.04.133}, author = {Ramana, Chepuri V. and Patel, Pitarnbar and Gonnade, Rajesh G.} } @article { ISI:000297737900020, title = {Synthesis and structural characterization of homochiral homo-oligomers of parent CIS- and trans-furanoid-beta-amino acids}, journal = {Chemistry-A European Journal}, volume = {17}, number = {46}, year = {2011}, month = {NOV}, pages = {12946-12954}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

The synthesis of homochiral homo-oligomers of cis- and trans-3-aminotetrahydrofuran-2-carboxylic acids (parent cis- and trans-furanoid-beta-amino acids, referred to as {\textquoteleft}{\textquoteleft}cis-/trans-FAA{\textquoteright}{\textquoteright}) has been carried out to understand their secondary structures and their dependence on the ring heteroatom. The oligomers of two diastereomers have been shown to have a distinct left-handed helicity. The cis-FAA homo-oligomers show a 14-helix structure, in contrast to the homo-oligomers of cis-ACPC, which adopt a sheet like structure. The trans-FAA homo-oligomers were found to adopt a 12-helix structure, the same trend found in trans-ACPC homo-oligomers. With the help of ab initio calculations, the structural features of cis-ACPC and cis-FAA hexamers were compared. We believe that the more compact packing of the cis-FAA hexapeptide should be due to a more favorable interaction between the ring and the backbone amide hydrogen.

}, keywords = {ab initio calculations, Amino acids, Density functional calculations, Peptides, secondary structures}, issn = {0947-6539}, doi = {10.1002/chem.201101855}, author = {Pandey, Sunil K. and Jogdand, Ganesh F. and Oliveira, Joao C. A. and Mata, Ricardo A. and Rajamohanan, Pattuparambil R. and Ramana, Chepuri V.} } @article { ISI:000303157400022, title = {Synthesis and structural characterization of homochiral homo-oligomers of cis-gamma-methoxy-substituted cis- and trans-furanoid-beta-amino acids}, journal = {European Journal of Organic Chemistry}, number = {13}, year = {2012}, month = {MAY}, pages = {2656-2663}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Herein we describe the synthesis of cis-/trans-3-aminotetrahydrofuran-2-carboxylic acids (cis-/trans-FAA) having a ?-methoxy group cis to the amine. The homo-oligomers of these two diastereomeric FAAs have been prepared. Preliminary investigation of their solution secondary structures revealed that they are the same as the homo-oligomers of the parent cis-/trans-FAA with the methoxy group only being a spectator substituent.

}, keywords = {Amino acids, helical structures, Oxygen heterocycles, Peptides}, issn = {1434-193X}, doi = {10.1002/ejoc.201101424}, author = {Giri, Awadut G. and Jogdand, Ganesh F. and Rajamohanan, Pattuparampil R. and Pandey, Sunil K. and Ramana, Chepuri V.} } @article { ISI:000326290300011, title = {Synthesis of C-disaccharides through a one-pot alkynol cycloisomerization-reductive deoxygenation}, journal = {Chemistry-A European Journal}, volume = {19}, number = {45}, year = {2013}, month = {NOV}, pages = {15109-15114}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {C-disaccharides, carbohydrates, Epoxide-alkyne coupling, Gold catalysis, Reductive deoxygenation}, issn = {0947-6539}, doi = {10.1002/chem.201302252}, author = {Narute, Sachin B. and Rout, Jeetendra Kumar and Ramana, Chepuri V.} } @article { ISI:000320709000004, title = {Synthesis of pseudo-indoxyl derivatives via sequential Cu-catalyzed SNAr and Smalley cyclization}, journal = {Chemical Communications}, volume = {49}, number = {57}, year = {2013}, month = {APR}, pages = {6376-6378}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

ortho-Bromophenyl sec-alkyl/sec-alkenyl ketones, on reaction with sodium azide in the presence of copper salts, undergo sequential SNAr followed by Smalley cyclization to provide pseudo-indoxyl derivatives. Some of these pseudo-indoxyl derivatives exhibit interesting fluorescent properties and broad Stokes shifts.

}, issn = {1359-7345}, doi = {10.1039/c3cc41348a}, author = {Goriya, Yogesh and Ramana, Chepuri V.} } @article {43167, title = {Synthesis of functionalized 6-hydroxy-2-oxindole derivatives by phenoxide cyclization}, journal = {Organic Letters}, volume = {18}, year = {2016}, month = {DEC}, pages = {6264-6267}, abstract = {An apparent intramolecular cross-dehydrogenative coupling of N-(3-hydrox)monoanilide of maleic esters comprising base promoted phenoxide cyclization and subsequent base-mediated aerobic oxidation was developed to synthesize a variety of 2-(6-hydroxy-2-oxoindolin-3-ylidene)-acetate derivatives. The isolation of intermediate cyclized products during the large scale reactions and their ready dehydrogenation with 1 equiv of base support this proposed two-step path.}, author = {Reddy, B. Narendraprasad and Ramana, Chepuri V.} } @article {49416, title = {Synthesis, characterization, and crystal structure of 2-(2-azido-phen-yl)-3-oxo-3H-indole 1-oxide}, journal = {Acta Crystallographica Section E Crystallographic Communications}, volume = {80}, year = {2024}, month = {MAR}, pages = {310-313}, abstract = {
An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen.
An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen, C14H8N4O2. In the crystal structure, weak C{\textemdash}H...O hydrogen bonds and π{\textendash}π stacking inter-actions link the mol-ecules. The structure exhibits disorder of the mol-ecule.

}, doi = {https://doi.org/10.1107/S2056989024001440}, author = {Dhote, Pawan and Tothadi, Srinu and Ramana, Chepuri V. and Chopra, D.} } @article {49304, title = {Synthesis of tetracyclic benzoxazolo-indol-3-ones from isatogens and arynes through a [3+2]-cycloaddition and skeletal reorganization}, journal = {Journal of Organic Chemistry}, volume = {89}, year = {2024}, month = {OCT }, pages = {14919-14928}, type = {Article}, abstract = {

The construction of an unprecedented tetracyclic benzoxazolo-indol-3-one scaffold has been executed through the [3 + 2]-cycloaddition of isatogens with arynes. The initially formed benzisoxazolo-indol-3-one intermediate undergoes a skeletal reorganization through a 1,3-sigmatropic shift/retro-Mannich reaction with the net formation of one C-N and two C-O bonds. The Lewis acid-catalyzed allylation of some of the resulting benzoxazolo-indol-3-ones resulted in oxazepino-indolones with promising photophysical properties.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.4c01667}, author = {Halnor, Swapnil V. and Singh, Maneesha and Dhote, Pawan S. and Ramana, Chepuri V.} }