@article { ISI:000355036400034, title = {Synthesis of naturally occurring (+)-osmundalactone and 4-epi-(+)-osmundalactone from triacetyl-O-D-glucal}, journal = {Tetrahedron Letters}, volume = {56}, number = {21}, year = {2015}, month = {MAY}, pages = {2783-2786}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient total synthesis of (+)-osmundalactone 1 has been achieved starting from readily available triacetyl-O-D-glucal 6 employing Ferrier rearrangement and Jones oxidation as key steps. Also, synthesis of 4-epi-(+)-osmundalactone 2 was accomplished from the common key intermediate 9. The absolute stereochemistry of (+)-osmundalactone 1 and a precursor of 4-epi-(+)-osmundalactone 2 have been established by single crystal X-ray analysis. The overall yield of compound 1 and 2 from triacetyl-O-D-glucal 6 is 13\% and 8\%, respectively. (C) 2015 Elsevier Ltd. All rights reserved.

}, keywords = {Bioactive molecules, carbohydrates, D-glucal, Ferrier rearrangement, Pyrones}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2015.04.038}, author = {Kotammagari, Tharun K. and Gonnade, Rajesh G. and Bhattacharya, Asish K.} } @article {43851, title = {Biomimetic total synthesis of angiopterlactone B and other potential natural products}, journal = {Organic Letters}, volume = {19}, year = {2017}, month = {JUL}, pages = {3564-3567}, type = {Article}, abstract = {A one-pot biomimetic synthesis of (-)-angiopterlactone B and its enantiomer (+)-angiopterlactone B has been accomplished via TBAF-catalyzed tandem ring contraction followed by oxa-Michael/Michael addition sequence. Comparison of specific optical rotations, absolute configurations, and CD spectra of natural, synthesized (-)-angiopterlactone B and (+)-angiopterlactone B unequivocally proves that the isolated angiopterlactone B must be levorotatory. Synthesis of hitherto undiscovered natural products 18 and 20 and analogues of angiopterlactone B demonstrate the versatility of this method.}, doi = {10.1021/acs.orglett.7b01525}, author = {Kotammagari, Tharun K. and Gonnade, Rajesh G. and Bhattacharya, Asish K.} } @article {46165, title = {Synthesis of artemisinin derived glycoconjugates inspired by click chemistry}, journal = {New Journal of Chemistry}, volume = {43}, year = {2019}, month = {MAR }, pages = {4017-4021}, type = {Article}, abstract = {

Herein we describe the synthesis of artemisinin based glycoconjugates (9a-i) through employing a Cu(i)-catalysed reaction between -propargylated dihydroartemisinin (7a) and azido sugars (8a-i), with moderate to excellent yields. Our synthesized artemisinin based glycoconjugates (9a-i) could prove to be an interesting class of bioactive molecules, suitable for the study of their various biological activities.

}, issn = {1144-0546}, doi = {10.1039/c8nj05737k}, author = {Goswami, Lakshmi and Paul, Sayantan and Kotammagari, Tharun K. and Bhattacharya, Asish K.} } @article {46410, title = {Unusual epimerization in styryllactones: synthesis of (-)-5-hydroxygoniothalamin, (-)-5-acetylgoniothalamin, and O-TBS-goniopypyrone}, journal = {ACS Omega}, volume = {4}, year = {2019}, month = {DEC}, pages = {22549-22556}, type = {Article}, abstract = {

(-)-5-Hydroxygoniothalamin, (-)-5-acetylgoniothalamin, and (+)-5-hydroxygoniothalamin, isolated from the Goniothalamus genus, are synthesized from triacetyl-O-D-glucal by employing the Ferrier reaction, Mitsunobu reaction, and Jones oxidation as key steps. The synthetic procedure also yields the epimers of (-)-5-hydroxygoniothalamin and (+)-5-hydroxygoniothalamin employing acid-mediated transition-metal-free epimerization at C-5 of styryllactones. Further studies reveal that the epimerization is facilitated by the phenyl group present on the styryllactones. Also, depending on the dihydroxylation reaction conditions, various analogues of saturated styryllactones are synthesized utilizing oxa-Michael reaction conditions.

}, issn = {2470-1343}, doi = {10.1021/acsomega.9b03263}, author = {Kotammagari, Tharun K. and Paul, Sayantan and Bhattacharya, Asish K.} } @article {46912, title = {Synthesis of artemisinic acid derived glycoconjugates and their anticancer studies}, journal = {Organic \& Biomolecular Chemistry}, volume = {18}, year = {2020}, month = {MAR}, pages = {2252-2263}, type = {Article}, abstract = {

Glycoconjugates, due to their diverse functions, are widely regarded as biologically important molecules. Artemisinic acid 1 occurs naturally in the plant Artemisia annua and is considered to be the biogenetic precursor of the antimalarial drug, artemisinin 2. We report herein the design and synthesis of diverse artemisinic acid derived glycoconjugates. We have synthesized 12-O-artemisinic acid-glycoconjugates (7a-k) and 12-N-artemisinic acid-glycoconjugates (8a-k) by utilizing Cu(i)-catalyzed azide-alkyne cycloaddition reactions (Click chemistry) with various synthesized sugar azides (6a-k) in good to excellent yields along with two fluorescently labeled compounds, 12-O-artemisinic acid-glycoconjugate 11 and 12-N-artemisinic acid-glycoconjugate 12, to investigate the mode of action of these compounds in biological systems. All the synthesized artemisinic acid glycoconjugates were assayed for their efficacy against the MCF7 cell line. Our anticancer studies indicated that all the synthesized compounds inhibited the growth of MCF7 cells in a dose dependent manner, barring compounds 4 and 7d. However, these compounds exhibit moderate cytotoxicity, as is evident from their IC50 values.

}, issn = {1477-0520}, doi = {10.1039/d0ob00216j}, author = {Kotammagari, Tharun K. and Paul, Sayantan and Barik, Ganesh K. and Santra, Manas K. and Bhattacharya, Asish K.} } @article {48317, title = {Accelerated Rauhut-Currier dimerization enabled the synthesis of (+/-)-incarvilleatone and anticancer studies}, journal = {Beilstein Journal of Organic Chemistry}, volume = {19}, year = {2023}, month = {FEB}, pages = {204-211}, type = {Article}, abstract = {

The total synthesis of racemic incarvilleatone has been achieved by utilizing unexplored accelerated Rauhut-Currier (RC) dimeriza-tion. The other key steps of the synthesis are oxa-Michael and aldol reactions in a tandem sequence. Racemic incarvilleatone was separated by chiral HPLC and the configuration of each enantiomer was determined by single-crystal X-ray analysis. In addition, a one-pot synthesis of (+/-)-incarviditone has been achieved from rac-rengyolone by using KHMDS as a base. We have also assessed the anticancer activity of all the synthesized compounds in breast cancer cells nonetheless, they exhibited very limited growth suppression activity.

}, keywords = {dimerization, incarviditone, incarvilleatone, oxa-Michael, Rauhut-Currier}, issn = {1860-5397}, doi = {10.3762/bjoc.19.19}, author = {Kotammagari, Tharun K. and Misra, Sweta and Paul, Sayantan and Kunte, Sunita and Gonnade, Rajesh G. and Santra, Manas K. and Bhattacharya, Asish K.} }