@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 {48146, title = {Design and synthesis of eugenol/isoeugenol glycoconjugates and other analogues as antifungal agents against Aspergillus fumigatus}, journal = {RSC Medicinal Chemistry}, volume = {13}, year = {2022}, month = {AUG}, pages = {955-962}, type = {Article}, abstract = {

Glycoconjugates are biologically significant molecules as they tend to serve a wide range of intra- and extra-cellular processes depending on their size and complexity. The secondary metabolites of the plant Myristica fragrans, eugenol and isoeugenol, have shown antifungal activities (IC50 1900 mu M). Therefore, we envisioned that glycoconjugates based on these two scaffolds could prove to be potent antifungal agents. Triazole-containing compounds have shown prominent activities as antifungal agents. Based on this, we opined that a Cu(i) catalyzed click reaction could serve as the bridging tool between a eugenol/isoeugenol moiety and sugars to synthesize eugenol/isoeugenol based glycoconjugates. In our present work, we have coupled propargylated eugenol/isoeugenol and azido sugar to furnish eugenol/isoeugenol based glycoconjugates. In another approach, we have carried out hydroxylation of the double bond of eugenol and subsequent azidation of a primary alcohol followed by intramolecular coupling reactions leading to various other analogues. All the synthesized compounds were assayed against an opportunistic pathogenic fungus, Aspergillus fumigatus. Among the synthesized compounds, two analogues have exhibited significant antifungal activities with IC50 values of 5.42 and 9.39 mu M, respectively. The study suggested that these two analogues inhibit cell wall-associated melanin hydrophobicity along with the number of conidia. The synthesized compounds were found to be non-cytotoxic to an untransformed cell line.

}, doi = {10.1039/d2md00138a}, author = {Goswami, Lakshmi and Gupta, Lovely and Paul, Sayantan and Vermani, Maansi and Vijayaraghavan, Pooja 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.} } @article {48300, title = {Design and synthesis of 1,3-diynes as potent antifungal agents against aspergillus fumigatus}, journal = {ChemMedChem}, volume = {18}, year = {2023}, month = {MAY }, type = {Article}, abstract = {

Eugenol and isoeugenol, secondary metabolites isolated from the plant Myristica fragrans have displayed antifungal activities against Aspergillus fumigatus (IC50 1900 mu M). Compounds having conjugated unsaturation have been of great use as antifungals i. e. amphotericin B, nystatin and terbinafine etc. Hence, in the present study, we have designed and synthesised 1,3-diynes by utilizing Glaser-Hay and Cadiot-Chodkiewicz coupling reactions to furnish possible antifungal agents. Synthesis of 1,6-diphenoxyhexa-2,4-diyne derivatives was achieved by Cu(I) catalysed coupling of propargylated eugenol, isoeugenol, guaiacol, vanillin and dihydrogenated eugenol or eugenol in good to excellent yields. All the synthesized compounds were evaluated against pathogenic fungus A. fumigatus. Among all the synthesized compounds, one of the compounds was found to be exhibiting promising antifungal activity with IC50 value of 7.75 mu M thereby suggesting that this type of scaffold could pave the way for developing new antifungal agents. The most active compound was found to be low cytotoxic when assayed against L-132 cancer cell line. Effect of the most active compound on ergosterol biosynthesis has also been studied. Also, the most active compound exhibited significant anti-biofilm activity although the concentration was found to be higher than its anti-fungal activity. Morphological changes in the biofilm were remarkable under confocal laser scanning microscopy.

}, keywords = {1, 3-Diynes, Antifungal agents, Aspergillus fumigatus, Cadiot-Chodkiewicz, Glaser-Hay}, issn = {1860-7179}, doi = {10.1002/cmdc.202300013}, author = {Goswami, Lakshmi and Gupta, Lovely and Paul, Sayantan and Vijayaraghavan, Pooja and Bhattacharya, Asish K.} } @article {48285, title = {Late-stage C(sp(2))-H arylation of artemisinic acid and arteannuin B: effect of olefin migration towards synthesis of C-13 arylated artemisinin derivatives}, journal = {Chemistry-An Asian Journal}, volume = {18}, year = {2023}, month = {APR }, type = {Article}, abstract = {

In recent years, C-H bond functionalization has emerged as a pivotal tool for late-stage functionalization of complex natural products for the synthesis of potent biologically active derivatives. Artemisinin and its C-12 functionalized semi-synthetic derivatives are well-known clinically used anti-malarial drugs due to the presence of the essential 1,2,4-trioxane pharmacophore. However, in the wake of parasite developing resistance against artemisinin-based drugs, we conceptualized the synthesis of C-13 functionalized artemisinin derivatives as new antimalarials. In this regard, we envisaged that artemisinic acid could be a suitable precursor for the synthesis of C-13 functionalized artemisinin derivatives. Herein, we report C-13 arylation of artemisinic acid, a sesquiterpene acid and our attempts towards synthesis of C-13 arylated artemisinin derivatives. However, all our efforts resulted in the formation of a novel ring-contracted rearranged product. Additionally, we have extended our developed protocol for C-13 arylation of arteannuin B, a sesquiterpene lactone epoxide considered to be the biogenetic precursor of artemisinic acid. Indeed, the synthesis of C-13 arylated arteannuin B renders our developed protocol to be effective in sesquiterpene lactone as well.

}, keywords = {Arteannuin B, Artemisinic acid, artemisinin, C-H functionalization, Pd-catalysis}, issn = {1861-4728}, doi = {10.1002/asia.202300162}, author = {Paul, Sayantan and Ghodake, Balaji M. M. and Bhattacharya, Asish K. K.} } @article {49320, title = {1,6-Conjugate addition of in situ generated aryldiazenes to p-quinone methides}, journal = {Organic \& Biomolecular Chemistry}, volume = {22}, year = {2024}, month = {JUL}, pages = {5636-5645}, type = {Article}, abstract = {

Herein we report a transition-metal free, base-mediated 1,6-conjugate addition of aryldiazenes to para-quinone methides (p-QMs). Arylhydrazines were used for the in situ generation of aryldiazenes using a base-mediated protocol in the presence of air as the oxidant. The 1,6-conjugate addition of aryldiazenes to para-quinone methides via a radical mechanism is followed by an oxidative rearrangement to furnish the desired product, arylhydrazones. Interestingly, our synthetic protocol results in the formation of an aryldiazene radical, which undergoes 1,6-conjugate addition with p-QMs to furnish the arylhydrazones.

}, issn = {1477-0520}, doi = {10.1039/d4ob00618f}, author = {Mamale, Ajay G. and Paul, Sayantan and Gonnade, Rajesh G. and Bhattacharya, Asish K.} } @article {49300, title = {Methanesulfonic acid-catalyzed friedel-crafts alkylation: towards sustainable synthesis of arylalkanes from donor-acceptor cyclopropane ketones}, journal = {Asian Journal of Organic Chemistry}, volume = {13}, year = {2024}, month = {JUL}, type = {Article}, abstract = {

We present herein Br \& oslash;nsted acid-catalyzed Friedel-Crafts alkylation of phenols with Donor-Acceptor cyclopropane ketones. The presence of the 1,4-diphenyl butan-1-one and 1,3-diphenyl propane-1-one motifs in various naturally occurring biologically significant molecules inspired us to pursue the direct synthesis of these structural frameworks. Utilizing methanesulfonic acid (MeSO3H) as a catalyst, we achieved a more environmentally friendly and high-yielding synthesis, owing to its cost-effectiveness, biodegradability, transition-metal and additives free conditions. Furthermore, we have successfully extended our developed methodology to thiophenols, resulting in the production of sulfur-based butan-1-one derivatives in good yields. The presence of 1,4-diphenyl butan-1-one and 1,3-diphenyl propane-1-one motifs in various naturally occurring biologically significant molecules prompted us to develop a Br \& oslash;nsted acid-catalyzed Friedel-Crafts alkylation of phenols with Donor-Acceptor cyclopropane. image

}, keywords = {donor-acceptor cyclopropane, Friedel-Crafts alkylation, methanesulfonic acid, Phenols, thiophenol}, issn = {2193-5807}, doi = {10.1002/ajoc.202400116}, author = {Goswami, Lakshmi and Paul, Sayantan and Mamale, Ajay G. and Gonnade, Rajesh G. and Bhattacharya, Asish K.} } @article {49043, title = {Short review on the synthetic routes for the antiepileptic drug (S)-levetiracetam}, journal = {Organic Process Research and Development }, volume = {28}, year = {2024}, month = {MAR }, pages = {924-936}, type = {Review}, abstract = {

Epilepsy is a chronic disorder characterized by recurrent unpredictable seizures. Levetiracetam (Keppra) was introduced by UCB for the treatment of partial onset seizures in patients above 16 years of age diagnosed with epilepsy. This review reports synthetic strategies available for the synthesis of (S)-levetiracetam and will certainly aid the quest for the development of new routes for its synthesis.

}, keywords = {antiepileptic drug, butyrolactam, epilepsy, levetiracetam, synthesis}, issn = {1083-6160}, doi = {10.1021/acs.oprd.4c00002}, author = {Paul, Sayantan and Bhattacharya, Asish K.} } @article {49275, title = {Strategies employing transition-metal free conditions for C-C bond formation in indoles}, journal = {ChemistrySelect}, volume = {9}, year = {2024}, month = {SEP}, pages = {e202403280}, type = {Review}, abstract = {

Indole motifs are omnipresent in nature and can be found in many natural products as well as pharmaceuticals. It is for this reason synthetic transformations of indole have become a topic of interest for the organic and medicinal chemist community for decades. In this review, we have emphasized the functionalization of indoles via transition-metal-free approaches. This review touches on many aspects in different sub-sections, which gives a proposition of the tactics employed for the functionalization of indoles and an overview of the road ahead. In this review, essentially transition-metal-free conditions for C-C bond formation reactions in indoles has been explored. This review describes various approaches of functionalization at the C-2, C-3, C-4 and C-7 position of indoles which comprises arylation, alkenylation, acylation, formylation, alkylation, bisindolyl and cyclization strategies. Also, strategies incorporating N-alkylation/arylation has also been covered. image

}, keywords = {Alkylation, Arylation, formylation, Indole, transition-metal free}, issn = {2365-6549}, doi = {10.1002/slct.202403280}, author = {Ghodake, Balaji M. and Paul, Sayantan and Bhattacharya, Asish K.} }