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  1. Article ; Online: Enantioselective Imine Reduction of Dihydro-β-carbolines by Fe-Thiosquaramide Catalyst.

    Sathish, Manda / Nachtigall, Fabiane M / Santos, Leonardo S

    Organic letters

    2022  Volume 24, Issue 41, Page(s) 7627–7631

    Abstract: Enantioselective imine reduction of dihydro-β-carbolines (DHBCs) is a reliable and powerful tool to construct bioactive chiral tetrahydro-β-carbolines (THBCs). Here, we report an efficient enantioselective imine reduction employing ... in situ ... ... ...

    Abstract Enantioselective imine reduction of dihydro-β-carbolines (DHBCs) is a reliable and powerful tool to construct bioactive chiral tetrahydro-β-carbolines (THBCs). Here, we report an efficient enantioselective imine reduction employing in situ generated Fe-thiosquaramides (Fe-TSQs) 3a and 3b as asymmetric organometallic catalysts to produce chiral THBCs (2a-h). The catalyst 3a at 15 mol % was found to be suitable for the substrates with alkyl and aryl groups which afford corresponding chiral THBCs with excellent enantioselectivities (up to ee 99%).
    MeSH term(s) Stereoisomerism ; Imines ; Carbolines ; Catalysis
    Chemical Substances Imines ; Carbolines
    Language English
    Publishing date 2022-10-11
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1523-7052
    ISSN (online) 1523-7052
    DOI 10.1021/acs.orglett.2c03093
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Air-Stable Cobalt(III) and Chromium(III) Complexes as Single-Component Catalysts for the Activation of Carbon Dioxide and Epoxides.

    Fonseca-López, Daniela / Ezenarro-Salcedo, David / Nachtigall, Fabiane M / Santos, Leonardo S / Macías, Mario A / Rojas, René S / Hurtado, John J

    Inorganic chemistry

    2024  

    Abstract: Cobalt(III) and chromium(III) salophen chloride complexes were synthesized and tested for the cycloaddition of carbon dioxide ( ... ...

    Abstract Cobalt(III) and chromium(III) salophen chloride complexes were synthesized and tested for the cycloaddition of carbon dioxide (CO
    Language English
    Publishing date 2024-04-26
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1484438-2
    ISSN 1520-510X ; 0020-1669
    ISSN (online) 1520-510X
    ISSN 0020-1669
    DOI 10.1021/acs.inorgchem.4c00151
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  3. Article ; Online: Nickel(II)-Catalyzed Formal [3+2] Cycloadditions between Indoles and Donor-Acceptor Cyclopropanes.

    Quezada, Víctor / Castroagudín, Mariña / Verdugo, Felipe / Ortiz, Sergio / Zaragoza, Guillermo / Nachtigall, Fabiane M / Reis, Francisco A A / Castro-Alvarez, Alejandro / Santos, Leonardo S / Nelson, Ronald

    Molecules (Basel, Switzerland)

    2024  Volume 29, Issue 7

    Abstract: This article describes the development of a nickel-catalyzed regio- and diastereoselective formal [3+2] cycloaddition ... ...

    Abstract This article describes the development of a nickel-catalyzed regio- and diastereoselective formal [3+2] cycloaddition between
    Language English
    Publishing date 2024-04-03
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1413402-0
    ISSN 1420-3049 ; 1431-5165 ; 1420-3049
    ISSN (online) 1420-3049
    ISSN 1431-5165 ; 1420-3049
    DOI 10.3390/molecules29071604
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Bifunctional thiosquaramide catalyzed asymmetric reduction of dihydro-β-carbolines and enantioselective synthesis of (-)-coerulescine and (-)-horsfiline by oxidative rearrangement.

    Sathish, Manda / Nachtigall, Fabiane M / Santos, Leonardo S

    RSC advances

    2020  Volume 10, Issue 63, Page(s) 38672–38677

    Abstract: Tetrahydro-β-carboline (THBC) is a tricyclic ring system that can be found in a large number of bioactive alkaloids. Herein, we report a simple and efficient method for the synthesis of enantiopure THBCs through a chiral thiosquaramide (11b) catalyzed ... ...

    Abstract Tetrahydro-β-carboline (THBC) is a tricyclic ring system that can be found in a large number of bioactive alkaloids. Herein, we report a simple and efficient method for the synthesis of enantiopure THBCs through a chiral thiosquaramide (11b) catalyzed imine reduction of dihydro-β-carbolines (17a-f). The
    Language English
    Publishing date 2020-10-21
    Publishing country England
    Document type Journal Article
    ISSN 2046-2069
    ISSN (online) 2046-2069
    DOI 10.1039/d0ra07705d
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Author Correction: Detection of SARS-CoV-2 in nasal swabs using MALDI-MS.

    Nachtigall, Fabiane M / Pereira, Alfredo / Trofymchuk, Oleksandra S / Santos, Leonardo S

    Nature biotechnology

    2020  Volume 38, Issue 10, Page(s) 1211

    Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper. ...

    Abstract An amendment to this paper has been published and can be accessed via a link at the top of the paper.
    Keywords covid19
    Language English
    Publishing date 2020-09-17
    Publishing country United States
    Document type Published Erratum
    ZDB-ID 1311932-1
    ISSN 1546-1696 ; 1087-0156
    ISSN (online) 1546-1696
    ISSN 1087-0156
    DOI 10.1038/s41587-020-0701-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 2167: Show issues Location:
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  6. Article ; Online: TCCA-mediated oxidative rearrangement of tetrahydro-β-carbolines: facile access to spirooxindoles and the total synthesis of (±)-coerulescine and (±)-horsfiline.

    Sathish, Manda / Sakla, Akash P / Nachtigall, Fabiane M / Santos, Leonardo S / Shankaraiah, Nagula

    RSC advances

    2021  Volume 11, Issue 27, Page(s) 16537–16546

    Abstract: Multi-reactive centered reagents are beneficial in chemical synthesis due to their advantage of minimal material utilization and formation of less by-products. Trichloroisocyanuric acid (TCCA), a reagent with three reactive centers, was employed in the ... ...

    Abstract Multi-reactive centered reagents are beneficial in chemical synthesis due to their advantage of minimal material utilization and formation of less by-products. Trichloroisocyanuric acid (TCCA), a reagent with three reactive centers, was employed in the synthesis of spirooxindoles through the oxidative rearrangement of various
    Language English
    Publishing date 2021-05-05
    Publishing country England
    Document type Journal Article
    ISSN 2046-2069
    ISSN (online) 2046-2069
    DOI 10.1039/d1ra02381k
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Detection of organic gunshot residues from human hands using direct sample analysis‐time of flight‐mass spectrometry

    González, Ricardo J. / Quispe, Cristina / Santos, Leonardo S. / Nachtigall, Fabiane M.

    Journal of mass spectrometry. 2022 May, v. 57, no. 5

    2022  

    Abstract: The organic gunshot residues (OGSRs), specifically methyl centralite (MC; 1,3‐dimethyl‐1,3‐diphenylurea), ethyl centralite (EC; 1,3‐diethyl‐1,3‐diphenylurea), 2,4‐DNT (2,4‐dinitrotoluene), and TNT (trinitrotoluene), are characteristic compounds for which ...

    Abstract The organic gunshot residues (OGSRs), specifically methyl centralite (MC; 1,3‐dimethyl‐1,3‐diphenylurea), ethyl centralite (EC; 1,3‐diethyl‐1,3‐diphenylurea), 2,4‐DNT (2,4‐dinitrotoluene), and TNT (trinitrotoluene), are characteristic compounds for which forensic analysts test determining if a person has discharged a firearm. A set of 200 samples from 50 shooters were collected as part of the validation study. Pistol 9 mm and special revolver .38 were fired at indoor and outdoor shooting ranges. The development of a methodology based on direct analysis of samples‐time of flight‐mass spectrometry (DSA‐TOF‐MS) made it possible to identify the main components of organic shot residues, which gave the possibility to introduce a new method of analysis of shot residues in the Chilean supply area. The DSA‐TOF‐MS provided extensive information on the composition of the shot residues: MC, EC, 2,4‐DNT, and TNT. Samples taken from the trigger hands required minimal sample preparation that reduced analyses time. With the implementation of new alternative analytical methodologies, a great step would be taken in the analysis of OGSRs, because now there is no such technique for its analysis in Chile, and the results would also complement the existing inorganic elemental analyses generated during a gunshot.
    Keywords forensic sciences ; humans ; mass spectrometry ; trinitrotoluene ; Chile
    Language English
    Dates of publication 2022-05
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1221763-3
    ISSN 1096-9888 ; 1076-5174
    ISSN (online) 1096-9888
    ISSN 1076-5174
    DOI 10.1002/jms.4824
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    Zs.A 4254: Show issues Location:
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  8. Article ; Online: Detection of SARS-CoV-2 in nasal swabs using MALDI-MS.

    Nachtigall, Fabiane M / Pereira, Alfredo / Trofymchuk, Oleksandra S / Santos, Leonardo S

    Nature biotechnology

    2020  Volume 38, Issue 10, Page(s) 1168–1173

    Abstract: Detection of SARS-CoV-2 using RT-PCR and other advanced methods can achieve high accuracy. However, their application is limited in countries that lack sufficient resources to handle large-scale testing during the COVID-19 pandemic. Here, we describe a ... ...

    Abstract Detection of SARS-CoV-2 using RT-PCR and other advanced methods can achieve high accuracy. However, their application is limited in countries that lack sufficient resources to handle large-scale testing during the COVID-19 pandemic. Here, we describe a method to detect SARS-CoV-2 in nasal swabs using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and machine learning analysis. This approach uses equipment and expertise commonly found in clinical laboratories in developing countries. We obtained mass spectra from a total of 362 samples (211 SARS-CoV-2-positive and 151 negative by RT-PCR) without prior sample preparation from three different laboratories. We tested two feature selection methods and six machine learning approaches to identify the top performing analysis approaches and determine the accuracy of SARS-CoV-2 detection. The support vector machine model provided the highest accuracy (93.9%), with 7% false positives and 5% false negatives. Our results suggest that MALDI-MS and machine learning analysis can be used to reliably detect SARS-CoV-2 in nasal swab samples.
    MeSH term(s) Algorithms ; Betacoronavirus/isolation & purification ; Biotechnology ; COVID-19 ; COVID-19 Testing ; Clinical Laboratory Techniques/methods ; Clinical Laboratory Techniques/statistics & numerical data ; Coronavirus Infections/diagnosis ; Coronavirus Infections/epidemiology ; Coronavirus Infections/virology ; Developing Countries ; False Negative Reactions ; False Positive Reactions ; Humans ; Machine Learning ; Nasal Mucosa/virology ; Pandemics ; Pneumonia, Viral/diagnosis ; Pneumonia, Viral/epidemiology ; Pneumonia, Viral/virology ; SARS-CoV-2 ; Sensitivity and Specificity ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/statistics & numerical data ; Support Vector Machine
    Keywords covid19
    Language English
    Publishing date 2020-07-30
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1311932-1
    ISSN 1546-1696 ; 1087-0156
    ISSN (online) 1546-1696
    ISSN 1087-0156
    DOI 10.1038/s41587-020-0644-7
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  9. Article: Bifunctional thiosquaramide catalyzed asymmetric reduction of dihydro-β-carbolines and enantioselective synthesis of (−)-coerulescine and (−)-horsfiline by oxidative rearrangement

    Sathish, Manda / Nachtigall, Fabiane M / Santos, Leonardo S

    RSC advances. 2020 Oct. 21, v. 10, no. 63

    2020  

    Abstract: Tetrahydro-β-carboline (THBC) is a tricyclic ring system that can be found in a large number of bioactive alkaloids. Herein, we report a simple and efficient method for the synthesis of enantiopure THBCs through a chiral thiosquaramide (11b) catalyzed ... ...

    Abstract Tetrahydro-β-carboline (THBC) is a tricyclic ring system that can be found in a large number of bioactive alkaloids. Herein, we report a simple and efficient method for the synthesis of enantiopure THBCs through a chiral thiosquaramide (11b) catalyzed imine reduction of dihydro-β-carbolines (17a–f). The in situ generated Pd–H employed as hydride source in the reaction of differently substituted chiral THBCs (18a–f) afforded high selectivities (R isomers, up to 96% ee) and good isolated yields (up to 88%). Moreover, the chiral thiosquaramide used also afforded exceptional catalyst activity in the syntheses of (−)-coerulescine (5) and (−)-horsfiline (6) with excellent enantioselectivities up to 98% and 93% ee, respectively, via an enantioselective oxidative rearrangement approach.
    Keywords catalytic activity ; enantiomers ; enantioselective synthesis ; enantioselectivity ; hydrides ; imines
    Language English
    Dates of publication 2020-1021
    Size p. 38672-38677.
    Publishing place The Royal Society of Chemistry
    Document type Article
    Note NAL-AP-2-clean
    ISSN 2046-2069
    DOI 10.1039/d0ra07705d
    Database NAL-Catalogue (AGRICOLA)

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  10. Article ; Online: MALDI coupled to modified traveling wave ion mobility mass spectrometry for fast enantiomeric determination.

    Nachtigall, Fabiane M / Rojas, Moises / Santos, Leonardo S

    Journal of mass spectrometry : JMS

    2018  Volume 53, Issue 8, Page(s) 693–699

    Abstract: In this work, the use of MALDI traveling wave ion mobility spectrometry-mass spectrometry (MALDI-TWIMS-MS) for stereoselective structural analysis of direct cleavage and identification of 2-substituted piperidines obtained through solid-phase asymmetric ... ...

    Abstract In this work, the use of MALDI traveling wave ion mobility spectrometry-mass spectrometry (MALDI-TWIMS-MS) for stereoselective structural analysis of direct cleavage and identification of 2-substituted piperidines obtained through solid-phase asymmetric synthesis by using heterogeneous 8-phenylmenthyl-based chiral auxiliary resins. A strategy for gas-phase chiral and structural characterization of small molecular weight molecules by using MALDI-IMS-MS technique is discussed. Because both MALDI and IMS do not directly offer chiral resolution, an easy methodology by adding a chiral phase is described to carry out in situ online ion/molecule complexation with different chiral analytes inside the mass spectrometer. Piperidine enantiomers were resolved, and separation obtained shows dependence of surface areas. To corroborate this assumption and elucidate the separation mechanism to accomplish an analytical technique by which fast determination of the chirality of molecules may be determined for a wide range organic compound applications, it was performed DFT calculations to determine the cross-sectional areas of proton-bound dimer complexes. Drift times are affected by cross-sectional areas, correlating bigger times with bigger molecular volumes during the ion mobility experiments of proton-bound dimer complexes.
    Language English
    Publishing date 2018-05-25
    Publishing country England
    Document type Journal Article
    ZDB-ID 1221763-3
    ISSN 1096-9888 ; 1076-5174
    ISSN (online) 1096-9888
    ISSN 1076-5174
    DOI 10.1002/jms.4206
    Database MEDical Literature Analysis and Retrieval System OnLINE

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