@article {46324, title = {Access to a stereoisomer library of solomonamide macrocycles}, journal = {Chemistry-An Asian Journal}, year = {2019}, month = {OCT}, type = {Article; Early Access}, abstract = {

In an attempt towards understanding stereo-structure activity relationships (SSARs), we have prepared eight possible stereoisomers of solomonamide macrocycles, in particular, by changing the stereochemical pattern of non-peptide fragment AHMOA. Here, we have demonstrated different ways to construct three contiguous chiral centers present in solomonamide B macrocycle using substrate/reagent-controlled methods. These methods involve Brown crotylation, NHK reaction and Evans aldol addition as key steps to synthesize key non-peptide fragment. Further, these non-peptide fragments were converted to their corresponding macrocycles via ligand-free intramolecular Heck reaction.

}, keywords = {Crotylation, Heck reaction, Inflammation, Macrocycles, Stereochemistry}, issn = {1861-4728}, doi = {10.1002/asia.201901075}, author = {Jachak, Gorakhnath R. and Athawale, Paresh R. and Choudhury, Rahul and Kashinath, K. and Reddy, D. Srinivasa} } @article {46631, title = {Total synthesis and absolute configuration determination of Ktedonoketone, a benzenoid metabolite from Thermophilic bacterium}, journal = {Tetrahedron Letters}, volume = {61}, year = {2020}, month = {NOV }, pages = {152526}, type = {Article}, abstract = {

The successful total synthesis of both enantiomers of ktedonoketone allowed us to decipher an unambiguous assignment of absolute configuration of the natural product. The concise synthesis highlights Wacker oxidation and aldol condensation as key steps. In addition to this, the current synthetic route is suitable to access a library of compounds on the similar skeleton as one can use readily available amino acids and Grignard reagents as variants. (C) 2020 Elsevier Ltd. All rights reserved.

}, keywords = {Absolute configuration, Ktedonoketone, Total synthesis, Wacker oxidation}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2020.152526}, author = {Dandawate, Monica and Choudhury, Rahul and Krishna, Gamidi Rama and Reddy, D. Srinivasa} } @article {47691, title = {Separation of a diastereomeric diol pair using the mechanical properties of crystals}, journal = {Crystengcomm}, volume = {23}, year = {2021}, month = {OCT}, pages = {7056-7060}, type = {Article}, abstract = {We report the separation of a (2S,3R/S)-3-ethyl-1-phenylhex-5-ene-2,3-diol (ephd) diastereomeric pair with visually indistinguishable acicular morphologies based on their mechanical responses, which is found to be more efficient than conventional separation methods. Furthermore, the molecular crystals of (2S,3R)-ephd show elastic deformation, while (2S,3S)-ephd fractures in a brittle manner under similar conditions.}, doi = {10.1039/d1ce01055g}, author = {Gamidi, Rama Krishna and Dandawate, Monica and Choudhury, Rahul and Tothadi, Srinu and Nangia, Ashwini and Reddy, D. Srinivasa} } @article {47672, title = {Total synthesis of a hypothetical macroketone of migrastatin}, journal = {European Journal of Organic Chemistry}, volume = {2021}, year = {2021}, month = {JUN }, pages = {3050-3053}, type = {Article}, abstract = {Danishefsky{\textquoteright}s macroketone, a simplified analogue of natural product Migrastatin, is one of the lead compounds with potent cancer cell migration inhibition potential. Different biological assays suggest fascin protein as the potential target. Although it was indicated through X-ray co-crystallography where the concerned macroketone analogue was found to bind in the actin-binding sites of fascin, there was a structural discrepancy, as the X-ray co-crystal structure suggested an E-olefin along with inversion of methyl stereochemistry from that of Danishefsky{\textquoteright}s macroketone. Here, we have accomplished the total synthesis of the {\textquoteleft}hypothetical macroketone{\textquoteright} for the first time. The TiCl4 mediated vinylogous Mukaiyama aldol reaction is the key step in present synthesis.}, keywords = {Hypothetical mecroketon, Metastasis, Migrastatin, RCM, vinylogous Mukaiyama aldol reaction (VMAR)}, issn = {1434-193X}, doi = {10.1002/ejoc.202100484}, author = {Choudhury, Rahul and Reddy, D. Srinivasa} } @article {48235, title = {Kupyaphores are zinc homeostatic metallophores required for colonization of Mycobacterium tuberculosis}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {119}, year = {2022}, month = {FEB}, pages = {e2110293119}, type = {Article}, abstract = {

Mycobacterium tuberculosis (Mtb) endures a combination of metal scarcity and toxicity throughout the human infection cycle, contributing to complex clinical manifestations. Pathogens counteract this paradoxical dysmetallostasis by producing specialized metal trafficking systems. Capture of extracellular metal by siderophores is a widely accepted mode of iron acquisition, and Mtb iron-chelating siderophores, mycobactin, have been known since 1965. Currently, it is not known whether Mtb produces zinc scavenging molecules. Here, we characterize low-molecular-weight zinc-binding compounds secreted and imported by Mtb for zinc acquisition. These molecules, termed kupyaphores, are produced by a 10.8 kbp biosynthetic cluster and consists of a dipeptide core of ornithine and phenylalaninol, where amino groups are acylated with isonitrilecontaining fatty acyl chains. Kupyaphores are stringently regulated and support Mtb survival under both nutritional deprivation and intoxication conditions. A kupyaphore-deficient Mtb strain is unable to mobilize sufficient zinc and shows reduced fitness upon infection. We observed early induction of kupyaphores in Mtb-infected mice lungs after infection, and these metabolites disappeared after 2 wk. Furthermore, we identify an Mtb-encoded isonitrile hydratase, which can possibly mediate intracellular zinc release through covalent modification of the isonitrile group of kupyaphores. Mtb clinical strains also produce kupyaphores during early passages. Our study thus uncovers a previously unknown zinc acquisition strategy of Mtb that could modulate host-pathogen interactions and disease outcome.

}, keywords = {metallophore, nutritional immunity, tuberculosis, zinc}, issn = {0027-8424}, doi = {10.1073/pnas.2110293119}, author = {Mehdiratta, Kritee and Singh, Shubham and Sharma, Sachin and Bhosale, Rashmi S. and Choudhury, Rahul and Masal, Dattatraya P. and Manocha, Alzu and Dhamale, Bhushan Dilip and Khan, Naseem and Asokachandran, Vivekanand and Sharma, Pooja and Ikeh, Melanie and Brown, Amanda C. and Parish, Tanya and Ojha, Anil K. and Michael, Joy Sarojini and Faruq, Mohammed and Medigeshi, Guruprasad R. and Mohanty, Debasisa and Reddy, D. Srinivasa and Natarajan, Vivek T. and Kamat, Siddhesh S. and Gokhale, Rajesh S.} } @article {48143, title = {Ready access to densely substituted furans using Tsuji-Wacker type cyclization}, journal = {Journal of Organic Chemistry}, volume = {87}, year = {2022}, month = {JAN }, pages = {556-568}, type = {Article}, abstract = {

A competent method for the construction of highly substituted furans catalyzed by Pd(II) and Cu(II) chloride has been developed. The method provides easy access to di-, tri-, and tetrasubstituted furans from corresponding diols with relatively mild conditions in a unified strategy. The developed method has been successfully tested with more than 25 substrates, which resulted in furans of multiple substitution patterns with up to 84\% isolated yields.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.1c02567}, author = {Masal, Dattatraya P. and Choudhury, Rahul and Singh, Aman and Reddy, D. Srinivasa} } @article {48985, title = {Comprehensive study on solomonamides: total synthesis, stereochemical revision, and SAR studies toward identification of simplified lead}, journal = {Journal of Organic Chemistry}, volume = {88}, year = {2023}, month = {DEC }, pages = {17088-17133}, type = {Article}, abstract = {

Solomonamides, a pair of macrocyclic peptide natural products originating from marine sources, have garnered significant attention within the synthetic community owing to their marked anti-inflammatory efficacy and intricate molecular architectures. In this paper, we present a very detailed investigation into solomonamides, including the challenges associated with the total synthesis, the evolution of our synthetic strategies, structural reassignment, synthesis of all possible stereoisomeric macrocycles, biological assessment, structure-activity relationship (SAR) studies, etc. Within the ambit of this total synthesis, diverse strategies for macrocyclization were rigorously explored, encompassing the Friedel-Crafts acylation, cyclization involving the aniline NH2 moiety, macrolactamization utilizing Gly-NH2, and Heck macrocyclization methodologies. In addition, an array of intriguing chemical transformations were devised, including but not limited to photo-Fries rearrangement, Wacker oxidation, ligand-free Heck macrocyclization, oxidative cleavage of indole, synthesis of contiguous stereocenters via substrate/reagent-controlled protocols, and simultaneous making and breaking of olefinic moieties. The findings of this investigation revealed a structurally simplified lead compound. Remarkably, the lead compound, while possessing structural simplification in comparison to the intricate solomonamide counterparts, demonstrates equipotent in vivo anti-inflammatory efficacy.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.3c01987}, author = {Jachak, Gorakhnath R. and Kashinath, K. and Vasudevan, N. and Athawale, Paresh R. and Choudhury, Rahul and Dange, Santoshkumar S. and Agarwal, Heena and Barthwal, Manoj Kumar and Reddy, D. Srinivasa} } @article {48801, title = {Total synthesis and absolute configuration determination of the α-glycosidase inhibitor (3S,4R)-6-Acetyl-3-hydroxy-2,2-dimethylchroman-4-yl (Z)-2-Methylbut-2-enoate from Ageratina grandifolia}, journal = {Journal of Natural Products}, volume = {86}, year = {2023}, month = {JUN}, pages = {1878-1883}, type = {Article}, abstract = {

Herein, we report the first total synthesis of \& alpha;-glycosidaseinhibitor (3R, 4S)-6-acetyl-3-hydroxy-2,2-dimethylchroman-4-yl(Z)-2-methylbut-2-enoate as well as its enantiomer.Our synthesis confirms the chromane structure separately proposedby Navarro-Vazquez and Mata, on the basis of DFT computations. Furthermore,our synthesis allowed us to determine the absolute configuration ofthe natural compound as (3S, 4R)and not (3R, 4S).

}, issn = {0163-3864}, doi = {10.1021/acs.jnatprod.3c00236}, author = {Dandawate, Monica and Choudhury, Rahul and Krishna, Gamidi Rama and Reddy, D. Srinivasa} } @article {49082, title = {Total synthesis and revision of stereochemistry of a natural benzo[g]isochromene stereodiad isolated from rubia philippinensis}, journal = {Organic Letters}, volume = {26}, year = {2024}, month = {MAR }, pages = {2574-2579}, type = {Article}, abstract = {

This study presents a total synthesis and revision of the stereochemical configuration of the conformationally flexible natural product benzo[g]isochromene stereodiad alongside its diastereomeric counterparts. The highlights of the synthesis are the TiCl4-mediated diastereoselective aldol reaction, Pd-catalyzed lactonization, and Schmidt glycosidation. Our efforts using total synthesis disclosed herein proved that a previously assigned structure required revision.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.4c00553}, author = {Choudhury, Rahul and Miriyala, Satya Ravi Teja and Resmi, K. R. and Sridhar, Balasubramanian and Kasa, S. R. Krishna Murthy and Reddy, D. Srinivasa} }