Honors & Awards


  • Awarded GATE - 2007, IIT-Kanpur (2007)
  • Awarded CSIR-Senior Research Fellow Award, Counsil Of Scientific Industrial Research - New Delhi, India (2009-2013)
  • Awarded Developing Countries fellowship for International Young Scientists, Chinese Academy Of Sciences (20013-2014)
  • Flubright Award, United States India Education Foundation, Sponsored by USA and India Government (2015 -2017)

Professional Education


  • Master of Philosophy, Pondicherry University (2007)
  • Bachelor of Science, University Of Madras (2004)
  • Doctor of Philosophy, Pondicherry University (2013)
  • Master of Science, Madurai-Kamaraj University (2006)
  • Doctor of Philosophy, Pondicherry University, Chemistry - Organic Chemistry (2013)

Current Research and Scholarly Interests


Design and synthesis of new chiral molecules for organometal catalysis or organocatalysis.

Fulbright Award

Lab Affiliations


Graduate and Fellowship Programs


All Publications


  • Synthesis of Chiral, Densely Substituted Pyrrolidones via Phosphine-Catalyzed Cycloisomerization. Organic letters Trost, B. M., Gnanamani, E., Hung, C. J., Kalnmals, C. A. 2019

    Abstract

    Densely substituted chiral pyrrolidones are synthesized via phosphine-catalyzed cycloisomerization of enantioenriched beta-amino ynones, which are prepared in a single step using a highly enantioselective Zn-ProPhenol-catalyzed Mannich reaction. The exocyclic alkenes in the cyclization products provide versatile handles for further transformations and typically form with good E/ Z selectivity. This cycloisomerization method can be performed in streamlined fashion, without purification of the intermediate Mannich adduct, and extends to anthranilic acid based scaffolds in addition to ProPhenol-derived Mannich adducts.

    View details for PubMedID 30829494

  • Direct Enantio- and Diastereoselective Vinylogous Addition of Butenolides to Chromones Catalyzed by Zn-ProPhenol. Journal of the American Chemical Society Trost, B. M., Gnanamani, E., Kalnmals, C. A., Hung, C. J., Tracy, J. S. 2019; 141 (4): 1489–93

    Abstract

    We report the first enantio- and diastereoselective 1,4-addition of butenolides to chromones. Both α,β- and β,γ-butenolide nucleophiles are compatible with the Zn-ProPhenol catalyst, and preactivation as the siloxyfurans is not required. The scope of electrophiles includes a variety of substituted chromones, as well as a thiochromone and a quinolone, and the resulting vinylogous addition products are generated in good yield (31 to 98%), diastereo- (3:1 to >30:1), and enantioselectivity (90:10 to 99:1 er). These Michael adducts allow rapid access to several natural product analogs, and can be easily transformed into a variety of other interesting scaffolds as well.

    View details for PubMedID 30642168

  • Direct Enantio- and Diastereoselective Vinylogous Addition of Butenolides to Chromones Catalyzed by Zn-ProPhenol Journal of the American Chemical Society Trost, B. M., Gnanamani, E., Kalnmals, C. A., Hung, C., Tracy, J. S. 2019

    View details for DOI 10.1021/jacs.8b13367

  • 1,4-Benzoquinone antimicrobial agents against Staphylococcus aureus and Mycobacterium tuberculosis derived from scorpion venom. Proceedings of the National Academy of Sciences of the United States of America Carcamo-Noriega, E. N., Sathyamoorthi, S., Banerjee, S., Gnanamani, E., Mendoza-Trujillo, M., Mata-Espinosa, D., Hernández-Pando, R., Veytia-Bucheli, J. I., Possani, L. D., Zare, R. N. 2019

    Abstract

    Two 1,4-benzoquinone derivatives, found in the venom of the scorpion Diplocentrus melici following exposure to air, have been isolated, characterized, synthesized, and assessed for antimicrobial activities. Initially a white, viscous liquid, the extracted venom colors within minutes under ambient conditions. From this colored mixture, two compounds, one red, the other blue, were isolated and purified using chromatography. After a variety of NMR and mass spectrometry experiments, the red compound was determined to be 3,5- dimethoxy-2-(methylthio)cyclohexa-2,5-diene-1,4-dione, and the blue compound was determined to be 5-methoxy-2,3- bis(methylthio)cyclohexa-2,5-diene-1,4-dione. Because extremely small amounts of these compounds were isolated from the scorpion venom, we developed laboratory syntheses from commercially available precursors, allowing us to produce sufficient quantities for crystallization and biological assays. The red benzoquinone is effective against Staphylococcus aureus [minimum inhibitory concentration (MIC) = 4 µg/mL], while the blue benzoquinone is active against Mycobacterium tuberculosis (MIC = 4 µg/mL) and even against a multidrug-resistant (MDR) strain with nearly equal effectiveness. The bactericidal effects of both benzoquinones show comparable activity to commercially available antibiotics used against these pathogens and were cytotoxic to neoplastic cell lines, suggesting their potential as lead compounds for the development of novel antimicrobial and anticancer drugs. Importantly, the blue benzoquinone was also effective in vivo with mouse models of MDR tuberculosis infection. After treatment for 2 mo, four mice with late-stage active MDR tuberculosis had a significant decrease in pulmonary bacillary loads and tissue damage. Healthy mice served as negative controls and tolerated treatment well, without adverse side effects.

    View details for DOI 10.1073/pnas.1812334116

    View details for PubMedID 31182590

  • An Alkaloid from Scorpion Venom: Chemical Structure and Synthesis. Journal of natural products Banerjee, S., Gnanamani, E., Lynch, S. R., Zuniga, F. Z., Jimenez-Vargas, J. M., Possani, L. D., Zare, R. N. 2018

    Abstract

    While most scorpion venom components identified in the past are peptidic or proteinic in nature, we report here a new alkaloid isolated from the venom of the Mexican scorpion Megacormus gertschi. Nuclear magnetic resonance and mass spectrometric investigations elucidate the structure of the alkaloid as ( Z)- N-(2-(1 H-imidazol-4-yl)ethyl)-3-(4-hydroxy-3-methoxyphenyl)-2-methoxyacrylamide (1). A chemical method of synthesizing this alkaloid is also described. Although abundant in venom, the above alkaloid was not found to have insecticidal activity. Structural analysis suggests that this venom alkaloid might be of potential interest for evaluating its medicinal effect.

    View details for PubMedID 30028606

  • Controlling Regioselectivity in the Enantioselective N-Alkylation of Indole Analogues Catalyzed by Dinuclear Zinc-ProPhenol. Angewandte Chemie (International ed. in English) Trost, B. M., Gnanamani, E., Hung, C. J. 2017; 56 (35): 10451–56

    Abstract

    The enantioselective N-alkylation of indole and its derivatives with aldimines is efficiently catalyzed by a zinc-ProPhenol dinuclear complex under mild conditions to afford N-alkylated indole derivatives in good yield (up to 86%) and excellent enantiomeric ratio (up to 99.5:0.5 e.r.). This method tolerates a wide array of indoles, as well as pyrrole and carbazole, to afford the corresponding N-alkylation products. The reaction can be run on a gram scale with reduced catalyst loading without impacting the efficiency. The chiral aminals were further elaborated into various chiral polyheterocyclic derivatives. The surprising stability of the chiral N-alkylation products will open new windows for asymmetric catalysis and medicinal chemistry.

    View details for PubMedID 28654735

  • Can all bulk-phase reactions be accelerated in microdroplets? ANALYST Banerjee, S., Gnanamani, E., Yan, X., Zare, R. N. 2017; 142 (9): 1399-1402

    Abstract

    Recent studies have shown that microdroplet reactions are markedly accelerated compared to the corresponding bulk-phase reactions. This raises the question whether all reactions can be sped up by this means. We present a counter example, and we show that the reaction mechanism in microdroplets can differ sharply from that in bulk, especially because of the distinct microdroplet surface environment. This analysis helps to guide us how to choose and control reactions in microdroplets and provides a possible perspective on utilizing microdroplet chemistry to scale up synthesis.

    View details for DOI 10.1039/c6an02225a

    View details for PubMedID 28332662

  • Zn-ProPhenol Catalyzed Enantio- and Diastereoselective Direct Vinylogous Mannich Reactions between α,β- and β,γ-Butenolides and Aldimines. Journal of the American Chemical Society Trost, B. M., Gnanamani, E., Tracy, J. S., Kalnmals, C. A. 2017; 139 (50): 18198–201

    Abstract

    We report a Zn-ProPhenol catalyzed reaction between butenolides and imines to obtain tetrasubstituted vinylogous Mannich products in good yield and diastereoselectivity with excellent enantioselectivity (97 to >99.5% ee). Notably, both α,β- and β,γ-butenolides can be utilized as nucleophiles in this transformation. The imine partner bears the synthetically versatile N-Cbz group, avoiding the use of the specialized aryl directing groups previously required in related work. Additionally, the reaction can be performed on gram scale with reduced catalyst loading as low as 2 mol %. The functional group-rich products can be further elaborated using a variety of methods.

    View details for PubMedID 29198100

  • Degradation intermediates of polyhydroxy butyrate inhibits phenotypic expression of virulence factors and biofilm formation in luminescent Vibrio sp. PUGSK8. NPJ biofilms and microbiomes Seghal Kiran, G., Priyadharshini, S., Dobson, A. D., Gnanamani, E., Selvin, J. 2016; 2: 16002

    Abstract

    Luminescent vibrios are ubiquitous in the marine environment and are the causative agents of vibriosis and mass mortality in many aquatic animals. In aquatic environments, treatments cannot be limited to the diseased population alone, therefore treatment of the entire aquatic system is the only possible approach. Thus, the use of antibiotics to treat part of the infected animals requires a dose based on the entire biomass, which results in the treatment of uninfected animals as well as non-target normal microbial flora. A treatment method based on anti-virulence or quorum quenching has recently been proposed as an effective treatment strategy for aquatic animals. Polyhydroxy butyrates (PHB) are bacterial storage molecules, which accumulate in cells under nutritional stress. The degradation of PHB releases short-chain β-hydroxy butyric acid, which may act as anti-infective molecule. To date, there is very limited information on the potential anti-infective and anti-virulence mechanisms involving PHB. In this study, we aim to examine the effect of PHB on inhibition of the virulence cascade of Vibrio such as biofilm formation, luminescence, motility behaviour, haemolysin and quorum sensing. A luminescent Vibrio PUGSK8, tentatively identified as Vibrio campbellii PUGSK8 was tested in vitro for production of extracellular virulence factors and then established as a potential shrimp pathogen based on in vivo challenge experiments. The ability of Vibrio PUGSK8 to form biofilms and the effect of PHB on biofilm formation was tested in a 96-well microtitre-plate assay system. The motility behaviour of Vibrio PUGSK8 was evaluated using twitching, swimming and swarming plate assays. Reporter strains such as Chromobacterium violaceum CV026 and Agrobacterium tumefaciens were used to detect quorum-sensing molecules. Gas chromatography-mass spectrometry spectral analysis was performed to elucidate the fragmentation pattern and structure of N-hexanoyl homoserine lactone. PHB depolymerase activity in Vibrio PUGSK8 was quantified as the amount of the enzyme solution to hydrolyse 1 μg of PHB per min. An in vivo challenge experiment was performed using a gnotobiotic Artemia assay. Of the 27 isolates tested, the Vibrio PUGSK8 strain was selected for target-specific assays based on the high intensity of luminescence and production of virulence factors. The virulence cascade detected in Vibrio PUGSK8 include luminescence, motility behaviour, biofilm formation, quorum sensing and haemolysin production. Thus inhibition/degradation of the virulence cascade would be an effective approach to contain Vibrio infections in aquatic animals. In this report, we demonstrate that the degradation intermediate of PHB effectively inhibits biofilm formation, luminescence, motility behaviour, haemolysin production and the N-acyl-homoserine lactone (AHL)-mediated quorum-sensing pathway in PUGSK8. Interestingly, the growth of Vibrio PUGSK8 remains unaffected in the presence of PHB, with PHB degradation being detected in the media. PHB depolymerase activity in Vibrio PUGSK8 results in the release of degradation intermediates include a short-chain β-hydroxy butyric acid, which inhibits the virulence cascade in Vibrio PUGSK8. Thus, a molecule that targets quorum sensing and the virulence cascade and which is species/strain-specific could prove to be an effective alternative to antimicrobial agents to control the pathogenesis of Vibrio, and thereby help to contain Vibrio outbreaks in aquatic systems.

    View details for PubMedID 28721241

    View details for PubMedCentralID PMC5515267