1
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Zhao Z, Popov S, Lee W, Burch JE, Delgadillo DA, Kim LJ, Shahgholi M, Lebrón-Acosta N, Houk KN, Nelson HM. Accessing Medium-Sized Rings via Vinyl Carbocation Intermediates. Org Lett 2024; 26:1000-1005. [PMID: 38295154 PMCID: PMC10863392 DOI: 10.1021/acs.orglett.3c04014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 02/02/2024]
Abstract
Medium-sized rings (8-11-membered cycles) are often more challenging to synthesize than smaller rings (5-7-membered cycles) due to ring strain. Herein, we report a catalytic method for forming 8- and 9-membered rings that proceeds via the intramolecular Friedel-Crafts reactions of vinyl carbocation intermediates. These reactive species are generated catalytically through the ionization of vinyl toluenesulfonates by a Lewis acidic lithium cation-weakly coordinating anion salt.
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Affiliation(s)
- Zhenqi Zhao
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Stasik Popov
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los Angeles, California 90095, United States
| | - Woojin Lee
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los Angeles, California 90095, United States
| | - Jessica E. Burch
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - David A. Delgadillo
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Lee Joon Kim
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los Angeles, California 90095, United States
| | - Mona Shahgholi
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Naiara Lebrón-Acosta
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - K. N. Houk
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, Los Angeles, California 90095, United States
| | - Hosea M. Nelson
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
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2
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Delgadillo D, Burch JE, Kim LJ, de Moraes LS, Niwa K, Williams J, Tang MJ, Lavallo VG, Khatri Chhetri B, Jones CG, Rodriguez IH, Signore JA, Marquez L, Bhanushali R, Woo S, Kubanek J, Quave C, Tang Y, Nelson HM. High-Throughput Identification of Crystalline Natural Products from Crude Extracts Enabled by Microarray Technology and microED. ACS Cent Sci 2024; 10:176-183. [PMID: 38292598 PMCID: PMC10823509 DOI: 10.1021/acscentsci.3c01365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 02/01/2024]
Abstract
The structural determination of natural products (NPs) can be arduous because of sample heterogeneity. This often demands iterative purification processes and characterization of complex molecules that may be available only in miniscule quantities. Microcrystal electron diffraction (microED) has recently shown promise as a method to solve crystal structures of NPs from nanogram quantities of analyte. However, its implementation in NP discovery remains hampered by sample throughput and purity requirements, akin to traditional NP-discovery workflows. In the methods described herein, we leverage the resolving power of transmission electron microscopy (TEM) and the miniaturization capabilities of deoxyribonucleic acid (DNA) microarray technology to address these challenges through the establishment of an NP screening platform, array electron diffraction (ArrayED). In this workflow, an array of high-performance liquid chromatography (HPLC) fractions taken from crude extracts was deposited onto TEM grids in picoliter-sized droplets. This multiplexing of analytes on TEM grids enables 1200 or more unique samples to be simultaneously inserted into a TEM instrument equipped with an autoloader. Selected area electron diffraction analysis of these microarrayed grids allows for the rapid identification of crystalline metabolites. In this study, ArrayED enabled structural characterization of 14 natural products, including four novel crystal structures and two novel polymorphs, from 20 crude extracts. Moreover, we identify several chemical species that would not be detected by standard mass spectrometry (MS) or ultraviolet-visible (UV/vis) spectroscopy and crystal forms that would not be characterized using traditional methods.
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Affiliation(s)
- David
A. Delgadillo
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Jessica E. Burch
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Lee Joon Kim
- Department of Chemistry
and Biochemistry, and Department of Chemical and Biomolecular
Engineering, University of California, Los
Angeles, Los Angeles, California 90095, United States
| | - Lygia S. de Moraes
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Kanji Niwa
- Department of Chemistry
and Biochemistry, and Department of Chemical and Biomolecular
Engineering, University of California, Los
Angeles, Los Angeles, California 90095, United States
| | - Jason Williams
- Department of Chemistry
and Biochemistry, and Department of Chemical and Biomolecular
Engineering, University of California, Los
Angeles, Los Angeles, California 90095, United States
| | - Melody J. Tang
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Vincent G. Lavallo
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Bhuwan Khatri Chhetri
- School
of Biological Sciences, School of Chemistry
and Biochemistry, and Neuroscience Program, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Christopher G. Jones
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Isabel Hernandez Rodriguez
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Joshua A. Signore
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Lewis Marquez
- Molecular
and Systems Pharmacology, Laney Graduate School, Emory University, Atlanta, Georgia 30322, United States
| | - Riya Bhanushali
- School
of Biological Sciences, School of Chemistry
and Biochemistry, and Neuroscience Program, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Sunmin Woo
- Center
for the Study of Human Health, Emory University, Atlanta, Georgia 30322, United States
| | - Julia Kubanek
- School
of Biological Sciences, School of Chemistry
and Biochemistry, and Neuroscience Program, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Cassandra Quave
- Molecular
and Systems Pharmacology, Laney Graduate School, Emory University, Atlanta, Georgia 30322, United States
- Center
for the Study of Human Health, Emory University, Atlanta, Georgia 30322, United States
- Department
of Dermatology, Emory University School
of Medicine, Atlanta, Georgia 30322, United
States
| | - Yi Tang
- Department of Chemistry
and Biochemistry, and Department of Chemical and Biomolecular
Engineering, University of California, Los
Angeles, Los Angeles, California 90095, United States
| | - Hosea M. Nelson
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
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3
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Yan C, Han W, Zhou Q, Niwa K, Tang MJ, Burch JE, Zhang Y, Delgadillo DA, Sun Z, Wu Z, Jacobsen SE, Nelson H, Houk KN, Tang Y. Genome Mining from Agriculturally Relevant Fungi Led to a d-Glucose Esterified Polyketide with a Terpene-like Core Structure. J Am Chem Soc 2023; 145:25080-25085. [PMID: 37948671 PMCID: PMC10682982 DOI: 10.1021/jacs.3c10179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/12/2023]
Abstract
Comparison of biosynthetic gene clusters (BGCs) found in devastating plant pathogens and biocontrol fungi revealed an uncharacterized and conserved polyketide BGC. Genome mining identified the associated metabolite to be treconorin, which has a terpene-like, trans-fused 5,7-bicyclic core that is proposed to derive from a (4 + 3) cycloaddition. The core is esterified with d-glucose, which derives from the glycosidic cleavage of a trehalose ester precursor. This glycomodification strategy is different from the commonly observed glycosylation of natural products.
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Affiliation(s)
- Chunsheng Yan
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Wenyu Han
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Qingyang Zhou
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Kanji Niwa
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Melody J. Tang
- Division of Chemistry
and Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Jessica E. Burch
- Division of Chemistry
and Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Yalong Zhang
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - David A. Delgadillo
- Division of Chemistry
and Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Zuodong Sun
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Zhongshou Wu
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Steven E. Jacobsen
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Hosea Nelson
- Division of Chemistry
and Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - K. N. Houk
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
| | - Yi Tang
- Department
of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, Department of Molecular,
Cell, and Developmental Biology, and Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, United States
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4
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Khatri Chhetri B, Mojib N, Moore SG, Delgadillo DA, Burch JE, Barrett NH, Gaul DA, Marquez L, Soapi K, Nelson HM, Quave CL, Kubanek J. Cryptic Chemical Variation in a Marine Red Alga as Revealed by Nontargeted Metabolomics. ACS Omega 2023; 8:13899-13910. [PMID: 37091395 PMCID: PMC10116502 DOI: 10.1021/acsomega.3c00301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 03/29/2023] [Indexed: 05/03/2023]
Abstract
Many marine algae occupy habitats that are dark, deep, or encrusted on other organisms and hence are frequently overlooked by natural product chemists. However, exploration of less-studied organisms can lead to new opportunities for drug discovery. Genetic variation at the individual, species, genus, and population levels as well as environmental influences on gene expression enable expansion of the chemical repertoire associated with a taxonomic group, enabling natural product exploration using innovative analytical methods. A nontargeted LC-MS and 1H NMR spectroscopy-based metabolomic study of 32 collections of representatives of the calcareous red algal genus Peyssonnelia from coral reef habitats in Fiji and the Solomon Islands revealed significant correlations between natural products' chemistry, phylogeny, and biomedically relevant biological activity. Hierarchical cluster analysis (HCA) of LC-MS data in conjunction with NMR profiling and MS/MS-based molecular networking revealed the presence of at least four distinct algal chemotypes within the genus Peyssonnelia. Two Fijian collections were prioritized for further analysis, leading to the isolation of three novel sulfated triterpene glycosides with a rearranged isomalabaricane carbon skeleton, guided by the metabolomic data. The discovery of peyssobaricanosides A-C (15-17) from two Fijian Peyssonnelia collections, but not from closely related specimens collected in the Solomon Islands that were otherwise chemically and phylogenetically very similar, alludes to population-level variation in secondary metabolite production. Our study reinforces the significance of exploring unusual ecological niches and showcases marine red algae as a chemically rich treasure trove.
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Affiliation(s)
- Bhuwan Khatri Chhetri
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Center
for Microbial Dynamics and Infection, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Nazia Mojib
- Department
of Biology, Spelman College, Atlanta, Georgia 30314, United States
| | - Samuel G. Moore
- Parker
H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - David A. Delgadillo
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Jessica E. Burch
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Nolan H. Barrett
- School
of Earth and Atmospheric Sciences, Atlanta, Georgia 30332, United States
| | - David A. Gaul
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Parker
H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Lewis Marquez
- Department
of Dermatology, Center for the Study of Human Health, and Antibiotic
Resistance Center, Emory University, Atlanta, Georgia 30322, United States
| | - Katy Soapi
- Institute
of Applied Sciences, University of South
Pacific, Suva, Fiji
| | - Hosea M. Nelson
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Cassandra L. Quave
- Department
of Dermatology, Center for the Study of Human Health, and Antibiotic
Resistance Center, Emory University, Atlanta, Georgia 30322, United States
| | - Julia Kubanek
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Center
for Microbial Dynamics and Infection, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
- School
of Biological Sciences, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Parker
H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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5
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Romero EO, Perkins JC, Burch JE, Delgadillo DA, Nelson HM, Narayan ARH. Chemoenzymatic Synthesis of (+)-Xyloketal B. Org Lett 2023; 25:1547-1552. [PMID: 36827601 DOI: 10.1021/acs.orglett.3c00334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Xyloketal B is a pentacyclic fungal marine natural product that has shown potential for the treatment of diseases such as Alzheimer's disease and atherosclerosis. Herein, we describe the first asymmetric synthesis of this natural product, which relies on a chemoenzymatic strategy. This approach leverages a biocatalytic benzylic hydroxylation to access to an ortho-quinone methide intermediate which is captured in a [4 + 2] cycloaddition to stereoselectively yield a key cyclic ketal intermediate enroute to (+)-xyloketal B. The relative configuration of this intermediate was rapidly confirmed as the desired stereoisomer using MicroED. To complete the synthesis, a second ortho-quinone methide was accessed through a reductive approach, ultimately leading to the stereoselective synthesis of (+)-xyloketal B.
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Affiliation(s)
- Evan O Romero
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.,Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jonathan C Perkins
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.,Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jessica E Burch
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - David A Delgadillo
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Hosea M Nelson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Alison R H Narayan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.,Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States.,Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109, United States
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6
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Curtis BJ, Kim LJ, Wrobel CJJ, Eagan JM, Smith RA, Burch JE, Le HH, Artyukhin AB, Nelson HM, Schroeder FC. Identification of Uric Acid Gluconucleoside-Ascaroside Conjugates in Caenorhabditis elegans by Combining Synthesis and MicroED. Org Lett 2020; 22:6724-6728. [PMID: 32820938 PMCID: PMC7526323 DOI: 10.1021/acs.orglett.0c02038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Few nucleoside-derived natural products have been identified from animals, despite the ubiquity of nucleosides in living organisms. Here, we use a combination of synthesis and the emerging electron microscopy technique microcrystal electron diffraction to determine the structures of several N3-(β-glucopyranosyl)uric acid derivatives in Caenorhabditis elegans. These noncanonical gluconucleosides further integrate an ascaroside moiety, for which we present a shortened synthetic route. The production of a phosphorylated gluconucleoside is influenced by evolutionarily conserved insulin signaling.
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Affiliation(s)
- Brian J Curtis
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Lee Joon Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Chester J J Wrobel
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - James M Eagan
- Ascribe Bioscience, Ithaca, New York 14853, United States
| | - Rubin A Smith
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Jessica E Burch
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Henry H Le
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Alexander B Artyukhin
- Chemistry Department, College of Environmental Science and Forestry, State University of New York, Syracuse, New York 13210, United States
| | - Hosea M Nelson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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7
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Stephens DE, Lakey-Beitia J, Burch JE, Arman HD, Larionov OV. Mechanistic insights into the potassium tert-butoxide-mediated synthesis of N-heterobiaryls. Chem Commun (Camb) 2018; 52:9945-8. [PMID: 27440397 DOI: 10.1039/c6cc04816a] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We report herein that symmetrical and non-symmetrical N-heterobiaryls are produced by a potassium tert-butoxide-mediated dimerization of heterocyclic N-oxides. The reaction is scalable and transition metal-free, and can be carried out under thermal and microwave conditions. Preliminary mechanistic studies point to the involvement of radical anionic intermediates arising from the N-oxide substrates and potassium tert-butoxide.
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Affiliation(s)
- David E Stephens
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
| | - Johant Lakey-Beitia
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA. and Centre for Biodiversity and Drug Discovery, Institute for Scientific Research and High Technology Services (INDICASAT-AIP), City of Knowledge, Panama City, Republic of Panama and Department of Biotechnology, Acharya Nagarjuna University, Nagarjuna Nagar, India
| | - Jessica E Burch
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
| | - Hadi D Arman
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
| | - Oleg V Larionov
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
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8
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Mfuh AM, Nguyen VT, Chhetri B, Burch JE, Doyle JD, Nesterov VN, Arman HD, Larionov OV. Additive- and Metal-Free, Predictably 1,2- and 1,3-Regioselective, Photoinduced Dual C-H/C-X Borylation of Haloarenes. J Am Chem Soc 2016; 138:8408-11. [PMID: 27347688 PMCID: PMC4958914 DOI: 10.1021/jacs.6b05436] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report herein a simple, additive- and metal-free, photoinduced, dual C-H/C-X borylation of chloro-, bromo-, and iodoarenes. The reaction produces 1,2- and 1,3-diborylarenes on gram scales under batch and continuous flow conditions. The regioselectivity of the dual C-H/C-X borylation is determined by the solvent and the substituents in the parent haloarenes.
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Affiliation(s)
- Adelphe M. Mfuh
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Vu T. Nguyen
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Bhuwan Chhetri
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Jessica E. Burch
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - John D. Doyle
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Vladimir N. Nesterov
- Department of Chemistry, University of North Texas, Denton, Texas 76201, United States
| | - Hadi D. Arman
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Oleg V. Larionov
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
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9
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Burch JE, Ahmed O, Hullin RP, Mindham RH. Antidepressive effect of amitriptyline treatment with plasma drug levels controlled within three different ranges. Psychopharmacology (Berl) 1988; 94:197-205. [PMID: 3127845 DOI: 10.1007/bf00176845] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Seventy-four depressed patients were treated with amitriptyline for 4-6 weeks. Their doses were individually adjusted to maintain the sum of the plasma levels of amitriptyline (AT) and nortriptyline (NT) within one of three different ranges, randomly allocated. Allowance was made for individual plasma binding of the drugs. In the 50 patients between 25 and 65 years of age, the antidepressive response at low plasma drug levels was somewhat poorer than at medium or high levels, which were equally effective. In this age group an association was found between outcome and the individual rate of AT metabolism, expressed as "reciprocal clearance" (RC), the steady-state plasma concentration of AT plus NT divided by the daily AT dose. Good antidepressive outcome was associated with high RC. The implications of these findings for patient treatment and for the interpretation of other studies are discussed. The 18 patients between 65 and 80 years of age showed no significant differences between the effectiveness of treatment at different plasma drug levels, and no significant associations between outcome and RC.
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Affiliation(s)
- J E Burch
- Department of Biochemistry, University of Leeds, West Yorkshire, UK
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10
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Abstract
Gas chromatography was used to determine plasma levels of amitriptyline, nortriptyline and their 10-hydroxy derivatives after conversion to the dehydro compounds by heating with acid. The primary amine 10-hydroxydesmethylnortriptyline is also dehydrated and the dehydro compound coincides on the chromatogram with dehydronortriptyline. Treatment of the extract with salicylaldehyde selectively removed the primary amine, which was determined by difference. Cis- and trans-hydroxydesmethylnortriptyline were isolated from urine by thin-layer chromatography and used to standardize the estimation. The stability of all the metabolites in plasma was investigated. Results are given for hydroxydesmethylnortriptyline levels in the plasma of 41 patients treated with amitriptyline.
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11
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Burch JE, Raddats MA, Roberts SG. Determination of desmethyl nortriptyline in plasma by gas chromatography before and after treatment with salicylaldehyde. J Chromatogr 1983; 274:350-4. [PMID: 6874839 DOI: 10.1016/s0378-4347(00)84442-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12
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Burch JE. The demethylation of amitriptyline: a cross-over study of steady-state plasma levels of amitriptyline and nortriptyline in depressed patients. Psychopharmacology (Berl) 1983; 80:254-8. [PMID: 6412270 DOI: 10.1007/bf00436164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Five elderly depressed patients were treated with amitriptyline (AT) and nortriptyline (NT) in turn, in a cross-over design. Steady-state plasma drug levels were compared with those calculated for eight healthy subjects of previous single-dose studies. Plasma clearances were on average about 2.5 times lower in the patients than the healthy subjects, but the ratios of the different reaction rates did not differ significantly between the two groups. The interpretation of the ratio of NT levels during AT treatment and NT treatment, in terms of the fraction of AT that is metabolised by demethylation, is discussed. The ratio of NT level to AT level during AT treatment was particularly variable between individuals. This was apparently due to independent variation in (a) the ratio of plasma clearances of AT and NT and (b) the fraction of AT metabolised to NT.
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Abstract
A single intramuscular (IM) dose of 50 mg amitriptyline (AT) was given to each of two healthy subjects who had previously taken three oral doses of AT tablets. The concentration-time curves of plasma nortriptyline (NT) arising from IM AT were fitted by computer to an equation based on the assumptions that NT is produced at a rate proportional to plasma AT concentration and is eliminated at a rate proportional to plasma NT concentration. The total amount of systemic NT produced was approximately equal for IM and oral AT doses, suggesting that the hepatic elimination of a given quantity of AT produces a constant amount of systemic NT, whether the AT is metabolised in the first pass or from the systemic circulation. This conclusion is supported by analysis of the time course of plasma NT concentration arising from oral AT doses. A large early production had previously been demonstrated and attributed to first-pass metabolism. The proportion of each oral AT dose eliminated in the first pass could now be estimated. Values ranged from 51% to 70% and were approximately equal to the proportion of the total NT apparently formed in the first pass.
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Burch JE, Hullin RP. Amitriptyline pharmacokinetics. Lentizol and ordinary amitriptyline tablets compared in a cross-over study of steady state plasma drug levels in depressed patients. J Pharm Pharmacol 1982; 34:260-1. [PMID: 6124602 DOI: 10.1111/j.2042-7158.1982.tb04239.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Burch JE, Shaw DM, Michalakeas A, Karajgi B, Roberts SG, Raddats MA. Time course of plasma drug levels during once-daily oral administration of clomipramine. Psychopharmacology (Berl) 1982; 77:344-7. [PMID: 6813895 DOI: 10.1007/bf00432768] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Fourteen depressed in-patients were treated with 150 mg clomipramine (CLO) daily, given as one oral dose. Using a gas-chromatographic method, concentrations of CLO and desmethyl clomipramine (DMCLO) were determined in plasma samples taken at frequent intervals during 24 h. The plasma level of each compound 12 h after the dose correlated well with the average value in the same patient, calculated over the whole 24-h period. Levels at other times gave poorer correlations, and at 24 h it was particularly poor. Plasma DMCLO concentrations were usually maximum 4-6 h after the dose. The ratios of maximum to minimum levels averaged only 1.31 +/- 0.15 SD. Peak CLO levels occurred 3 or 4 h after the dose. Maximum; minimum ratios averaged 2.72 +/- 0.73 SD, contrasting with the much smaller fluctuations of plasma nortriptyline (NT) levels observed in patients given this drug once daily. The difference is not due to a shorter half-life of CLO, but to the absorption and/or distribution behaviour of the two drugs. Although not fully understood, this difference between tertiary and secondary amines appears to hold generally among the tricyclic antidepressants.
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Abstract
Six healthy volunteers were given single doses of amitriptyline (AT) and of nortriptyline (NT) separated by at least 10 days. Plasma concentrations of both compounds were measured at intervals for 48 or 72 h. The total areas under the concentration-time curves for the ingested drug were greater for NT, but AT concentrations showed much higher peak values and took more than 12 h to reach the terminal beta phase of elimination. Doses of 50 mg AT produced areas averaging slightly less than half those for 100 mg AT in the same subject, suggesting some saturation of the elimination process. The consumption of a large, fatty meal just before taking the AT tablets had little effect on the plasma drug concentration curves. NT half-lives, measured after ingestion of NT tablets, were used in analysing the production of NT from doses of AT in the same subject. There was a rapid early production, amounting to 30-67% of the total and presumably resulting from the first pass of AT through the liver. NT was then formed continuously at a rate always proportional to the simultaneous rate of AT elimination. The total amount of NT entering the systemic circulation was about one-quarter of the AT dose.
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Burch JE, Roberts SG, Raddats MA. Binding of amitriptyline and nortriptyline in plasma determined from their equilibrium distributions between red cells and plasma, and between red cells and buffer solution. Psychopharmacology (Berl) 1981; 75:262-72. [PMID: 6798617 DOI: 10.1007/bf00432436] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In a new method for the measurement of plasma binding, amitriptyline (AT) and nortriptyline (NT) were allowed to reach equilibrium distribution between the cells and plasma of whole blood. A separate sample of the cells was equilibrated with a buffer solution containing the drugs. From the two distribution ratios for each drug, the fraction free in the plasma was calculated. Equilibria were achieved rapidly, avoiding denaturation of binding proteins. The pH was adequately controlled and the composition of the plasma was not altered by the experimental procedures. Large volumes of buffer solution gave amounts of free drug readily measurable by gas chromatography. Duplicate determinations showed coefficients of variation of 6% and 4.8% respectively for the free fractions of AT and NT in a given plasma sample. In 51 subjects the mean percentage of AT free in plasma was 4.31 +/- 0.59 SD and, of NT, 8.59 +/- 0.86. Binding was independent of drug concentration in the therapeutic range and did not differ between males and females nor between patients and normal subjects. It increased slightly with age. It was not affected by chylomicrons in the blood.
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Abstract
Two separate single doses of Lentizol (W. R. Warner, Pontypool, U.K.), a sustained-release preparation of amitriptyline (AT) were taken by each of six healthy subjects. Plasma concentrations of AT and of nortriptyline (NT) were determined at intervals over a period of 48 or 72 h. Faeces were collected and their drug content measured. Results were compared with those obtained when the same subjects took ordinary AT tablets. AT was found in the faeces after the ingestion of Lentizol or of ordinary AT tablets. However, after NT tablets negligible amounts of NT appeared in the faeces. AT was sometimes absorbed slowly from Lentizol, but on other occasions it was absorbed as rapidly as from ordinary tablets. Plasma levels of AT 24 h after the dose were usually not higher after Lentizol than after an equal dose of ordinary tablets. The systemic bioavailability of Lentizol as judged by areas under the plasma concentration-time curves, both for AT and for the NT formed metabolically, was on average lower than that of the ordinary tablets. However, the amounts of AT found in the faeces were not large enough to account for the AT area reduction by simple failure of absorption. Possible explanations of the discrepancy are discussed.
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Burch JE, Raddats MA, Thompson SG. Reliable routine method for the determination of plasma amitriptyline and nortriptyline by gas chromatography. J Chromatogr 1979; 162:351-6. [PMID: 528600 DOI: 10.1016/s0378-4347(00)81521-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A gas chromatographic method has been developed for the determination of amitriptyline and nortriptyline in plasma. OV-17 is used in a 1 m long packed column, with a flame ionization detector and an electronic integrator. Five internal standards are added. The base-specific extraction procedure and the method of calibrating the chromatograph are described in detail. The accuracy, precision and reliability of the method are demonstrated by the results of nearly 700 determinations of each drug, at concentrations ranging from 5 to 400 ng/ml in the plasma. An interlaboratory comparison with a double radioactive isotope derivative assay for nortriptyline has also shown satisfactory agreement.
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