2024-03-29T06:25:30Zhttp://repository.helmholtz-hzi.de/oai/requestoai:repository.helmholtz-hzi.de:10033/129392019-08-30T11:34:18Zcom_10033_620653col_10033_620654
Synthesis of the northern hemisphere of amphidinolide H2
Liesener, F.P.
Jannsen, U.
Kalesse, M.
2007-07-26T09:29:44Z
2007-07-26T09:29:44Z
2006
Article
Synthesis 2006, 2006:15:2590-2602
00397881,1437210X
10.1055/s-2006-942459
http://hdl.handle.net/10033/12939
n/a
505523 bytes
application/pdf
YES
Thieme
oai:repository.helmholtz-hzi.de:10033/137882019-08-30T11:31:47Zcom_10033_620653col_10033_620654
Thiourea-catalyzed direct reductive amination of aldehydes
Menche, Dirk
Arikan, Fatih
2007-09-25T13:22:01Z
2007-09-25T13:22:01Z
2007-09-25T13:22:01Z
Article
Synlett 2006, 2006:6:841-844
9365214,14372096
10.1055/s-2006-939052
http://hdl.handle.net/10033/13788
n/a
155741 bytes
application/pdf
YES
Thieme
oai:repository.helmholtz-hzi.de:10033/984962019-08-30T11:36:05Zcom_10033_620653col_10033_620654
Stereoselective total synthesis of etnangien and etnangien methyl ester.
Li, Pengfei
Li, Jun
Arikan, Fatih
Ahlbrecht, Wiebke
Dieckmann, Michael
Menche, Dirk
Institut für Organische Chemie, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany.
A highly stereoselective joint total synthesis of the potent polyketide macrolide antibiotics etnangien and etnangien methyl ester was accomplished by a convergent strategy and proceeds in 23 steps (longest linear sequence). Notable synthetic features include a sequence of highly stereoselective substrate-controlled aldol reactions to set the characteristic assembly of methyl- and hydroxyl-bearing stereogenic centers of the propionate portions, an efficient diastereoselective Heck macrocyclization of a deliberately conformationally biased precursor, and a late-stage introduction of the labile side chain by means of a high-yielding Stille coupling of protective-group-free precursors. Along the way, an improved, reliable protocol for a Z-selective Stork-Zhao-Wittig olefination of aldehydes was developed, and an effective protocol for a 1,3-syn reduction of sterically particularly hindered beta-hydroxy ketones was devised. Within the synthetic campaign, a more detailed understanding of the intrinsic isomerization pathways of these labile natural products was elaborated. The expedient and flexible strategy of the etnangiens should be amenable to designed analogues of these RNA-polymerase inhibitors, thus enabling further exploration of the promising biological potential of these macrolide antibiotics.
2010-05-11T13:06:53Z
2010-05-11T13:06:53Z
2010-04-16
Article
Stereoselective total synthesis of etnangien and etnangien methyl ester. 2010, 75 (8):2429-44 J. Org. Chem.
1520-6904
20334428
10.1021/jo100201f
http://hdl.handle.net/10033/98496
The Journal of organic chemistry
en
oai:repository.helmholtz-hzi.de:10033/1347152019-08-30T11:26:13Zcom_10033_620653col_10033_620654
Mode of action of epoxyphomalins A and B and characterization of related metabolites from the marine-derived fungus Paraconiothyrium sp.
Mohamed, Ietidal E
Kehraus, Stefan
Krick, Anja
König, Gabriele M
Kelter, Gerhard
Maier, Armin
Fiebig, Heinz-Herbert
Kalesse, Markus
Malek, Nisar P
Gross, Harald
Department of Botany, University of Khartoum, Khartoum, Sudan.
Antineoplastic Agents
Ascomycota
Caspases
Drug Screening Assays, Antitumor
Humans
Macrolides
Male
Marine Biology
Molecular Structure
Nuclear Magnetic Resonance, Biomolecular
Proteasome Endopeptidase Complex
Epoxyphomalins A (1) and B (2) are highly potent cytotoxic fungal metabolites. During the course of purifying larger quantities of 1 and 2 from Paraconiothyrium sp. fermentation extracts, three new epoxyphomalins (3-5) were isolated and characterized, showing modifications to the oxidation pattern of the cyclohexene moiety or of C-9 of the decalin system. IC(50) values for cytotoxicity against a panel of 36 human tumor cell lines were determined for all new compounds. Compound 4 was found to be cytotoxic particularly toward prostate PC3M (IC(50) = 0.72 μM) and bladder BXF 1218 L (IC(50) = 1.43 μM) cancer cell lines. In addition, inhibition of chymotrypsin-, caspase-, and trypsin-like activity of purified 20S proteasomes was determined for epoxyphomalins A (1) and B (2). The results indicate that compounds 1 and 2 exert their cytotoxic effect through potent inhibition of the 20S proteasome.
2011-06-28T14:37:49Z
2011-06-28T14:37:49Z
2010-12-27
Article
Mode of action of epoxyphomalins A and B and characterization of related metabolites from the marine-derived fungus Paraconiothyrium sp. 2010, 73 (12):2053-6 J. Nat. Prod.
1520-6025
21114274
10.1021/np100310k
http://hdl.handle.net/10033/134715
Journal of natural products
en
oai:repository.helmholtz-hzi.de:10033/2930892019-08-30T11:35:14Zcom_10033_620653col_10033_620654
Total synthesis of antibiotics: recent achievements, limitations, and perspectives.
Prusov, Evgeny V
Helmholtz Zentrum für Infektionsforschung, Braunschweig, Germany. Evgeny.Prusov@helmholtz-hzi.de
Several recently accomplished total syntheses of antibiotic natural products were summarized in this review in order to present current trends in this area of research. Compounds from different substance classes, including polyketide, depsipeptide, polyketide-polypeptide hybrid, and saccharide, were chosen to demonstrate the advancement in both chemical methodology and corresponding synthetic strategy.
2013-05-30T14:23:41Z
2013-05-30T14:23:41Z
2013-04
Article
Total synthesis of antibiotics: recent achievements, limitations, and perspectives. 2013, 97 (7):2773-95 Appl. Microbiol. Biotechnol.
1432-0614
23435901
10.1007/s00253-013-4757-5
http://hdl.handle.net/10033/293089
Applied microbiology and biotechnology
en
Archived with thanks to Applied microbiology and biotechnology
oai:repository.helmholtz-hzi.de:10033/3109942019-08-30T11:31:49Zcom_10033_620653col_10033_620654
Synthesis of the spiroketal core of integramycin.
Prusov, Evgeny V
Department of Medicinal Chemistry, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
A concise synthetic strategy towards the spiroketal core of the HIV-integrase inhibitor integramycin (1) was developed. The required ketone precursor was efficiently constructed from two simple and easily accessible subunits by means of a hydrozirconation/copper catalyzed acylation reaction. The effects of different protecting groups on the spiroketalization step were also investigated.
2014-01-07T10:11:33Z
2014-01-07T10:11:33Z
2013
Article
Synthesis of the spiroketal core of integramycin. 2013, 9:2446-50 Beilstein J Org Chem
1860-5397
24367411
10.3762/bjoc.9.282
http://hdl.handle.net/10033/310994
Beilstein journal of organic chemistry
en
Archived with thanks to Beilstein journal of organic chemistry
oai:repository.helmholtz-hzi.de:10033/5765902019-08-30T11:27:46Zcom_10033_620653col_10033_620654
A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids.
Trenner, Johanna
Prusov, Evgeny V
Helmholtz Centre for infection research, Inhoffenstr. 7, D-38124 Braunschweig, Germany.
Oxidation of the bisenolates of 3-acyltetramic acid to the corresponding 5-hydroxylated compounds using molecular oxygen is reported. The deprotection of the resulting compounds was also achieved.
2015-09-03T14:35:34Z
2015-09-03T14:35:34Z
2015
Article
A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids. 2015, 11:323-7 Beilstein J Org Chem
1860-5397
25815086
10.3762/bjoc.11.37
http://hdl.handle.net/10033/576590
Beilstein journal of organic chemistry
en
oai:repository.helmholtz-hzi.de:10033/6210082019-08-30T11:33:30Zcom_10033_620653col_10033_620654
RNA polymerase motions during promoter melting.
Feklistov, Andrey
Bae, Brian
Hauver, Jesse
Lass-Napiorkowska, Agnieszka
Kalesse, Markus
Glaus, Florian
Altmann, Karl-Heinz
Heyduk, Tomasz
Landick, Robert
Darst, Seth A
Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany.
All cellular RNA polymerases (RNAPs), from those of bacteria to those of man, possess a clamp that can open and close, and it has been assumed that the open RNAP separates promoter DNA strands and then closes to establish a tight grip on the DNA template. Here, we resolve successive motions of the initiating bacterial RNAP by studying real-time signatures of fluorescent reporters placed on RNAP and DNA in the presence of ligands locking the clamp in distinct conformations. We report evidence for an unexpected and obligatory step early in the initiation involving a transient clamp closure as a prerequisite for DNA melting. We also present a 2.6-angstrom crystal structure of a late-initiation intermediate harboring a rotationally unconstrained downstream DNA duplex within the open RNAP active site cleft. Our findings explain how RNAP thermal motions control the promoter search and drive DNA melting in the absence of external energy sources.
2017-07-11T14:46:33Z
2017-07-11T14:46:33Z
2017-05-26
Article
RNA polymerase motions during promoter melting. 2017, 356 (6340):863-866 Science
1095-9203
28546214
10.1126/science.aam7858
http://hdl.handle.net/10033/621008
Science (New York, N.Y.)
en
nfo:eu-repo/grantAgreement/EC/FP7/ 260872
openAccess
http://creativecommons.org/licenses/by-nc-sa/4.0/
oai:repository.helmholtz-hzi.de:10033/6211292019-08-30T11:25:43Zcom_10033_620653col_10033_620654
Total Synthesis of Nannocystin Ax.
Poock, Caroline
Kalesse, Markus
Hemholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany.
The total synthesis of nannocystin Ax in an overall yield of 11% with 14 steps as the longest linear sequence is reported. Nannocystin Ax is a cytotoxic 21-membered depsipeptide and was isolated from the myxobacterial genus Nannocystis sp. The synthesis uses a vinylogous Horner-Wadsworth-Emmons reaction (HWE) and a vinylogous Mukaiyama aldol reaction (VMAR) as the key steps for the construction of the polyketide fragment. The macrocycle was closed via a macrolactamization reaction using COMU.
2017-10-06T09:33:07Z
2017-10-06T09:33:07Z
2017-09-01
Article
Total Synthesis of Nannocystin Ax. 2017, 19 (17):4536-4539 Org. Lett.
1523-7052
28809579
10.1021/acs.orglett.7b02112
http://hdl.handle.net/10033/621129
Organic letters
en
http://creativecommons.org/licenses/by-nc-sa/4.0/
oai:repository.helmholtz-hzi.de:10033/6215252019-08-30T11:29:11Zcom_10033_620653col_10033_620654
Photocontrol of Antibacterial Activity: Shifting from UV to Red Light Activation.
Wegener, Michael
Hansen, Mickel J
Driessen, Arnold J M
Szymanski, Wiktor
Feringa, Ben L
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
The field of photopharmacology aims to introduce smart drugs that, through the incorporation of molecular photoswitches, allow for the remote spatial and temporal control of bioactivity by light. This concept could be particularly beneficial in the treatment of bacterial infections, by reducing the systemic and environmental side effects of antibiotics. A major concern in the realization of such light-responsive drugs is the wavelength of the light that is applied. Studies on the photocontrol of biologically active agents mostly rely on UV light, which is cytotoxic and poorly suited for tissue penetration. In our efforts to develop photoswitchable antibiotics, we introduce here antibacterial agents whose activity can be controlled by visible light, while getting into the therapeutic window. For that purpose, a UV-light-responsive core structure based on diaminopyrimidines with suitable antibacterial properties was identified. Subsequent modification of an azobenzene photoswitch moiety led to structures that allowed us to control their activity against Escherichia coli in both directions with light in the visible region. For the first time, full in situ photocontrol of antibacterial activity in the presence of bacteria was attained with green and violet light. Most remarkably, one of the diaminopyrimidines revealed an at least 8-fold difference in activity before and after irradiation with red light at 652 nm, showcasing the effective "activation" of a biological agent otherwise inactive within the investigated concentration range, and doing so with red light in the therapeutic window.
2018-10-30T14:38:17Z
2018-10-30T14:38:17Z
2017-12-13
Article
1520-5126
29136373
10.1021/jacs.7b09281
http://hdl.handle.net/10033/621525
Attribution-NonCommercial-ShareAlike 3.0 United States
http://creativecommons.org/licenses/by-nc-sa/3.0/us/
Journal of the American Chemical Society
oai:repository.helmholtz-hzi.de:10033/6216542019-08-30T11:34:20Zcom_10033_620653col_10033_620654
Tris(acetylacetonato) Iron(III): Recent Developments and Synthetic Applications
Lübken, Dennis
Saxarra, Marius
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
Tris(acetylacetonato) iron(III) [Fe(acac)3] is an indispensable reagent in synthetic chemistry. Its applications range from hydrogen atom transfer to cross-coupling reactions and to use as a Lewis acid. Consequently, the exceptional utility of Fe(acac)3 has been demonstrated in several total syntheses. This short review summarizes the applications of Fe(acac)3 in methodology and catalysis and highlights its use for the synthesis of medicinally relevant structures and in natural product syntheses.
2019-01-16T13:49:58Z
2019-01-16T13:49:58Z
2018-11-27
Article
0039-7881
1437-210X
10.1055/s-0037-1610393
http://hdl.handle.net/10033/621654
Synthesis
http://www.thieme-connect.de/DOI/DOI?10.1055/s-0037-1610393
Attribution-NonCommercial-ShareAlike 4.0 International
http://creativecommons.org/licenses/by-nc-sa/4.0/
Thieme
51
01
161
177
Synthesis
oai:repository.helmholtz-hzi.de:10033/6216642019-08-30T11:33:27Zcom_10033_620653col_10033_620654
A functional interplay between intein and extein sequences in protein splicing compensates for the essential block B histidine
Friedel, Kristina
Popp, Monika A.
Matern, Julian C. J.
Gazdag, Emerich M.
Thiel, Ilka V.
Volkmann, Gerrit
Blankenfeldt, Wulf
Mootz, Henning D.
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
Inteins remove themselves from a precursor protein by protein splicing. Due to the concomitant structural changes of the host protein, this self-processing reaction has enabled many applications in protein biotechnology and chemical biology. We show that the evolved M86 mutant of the Ssp DnaB intein displays a significantly improved tolerance towards non-native amino acids at the N-terminally flanking (−1) extein position compared to the parent intein, in the form of both an artificially trans-splicing split intein and the cis-splicing mini-intein. Surprisingly, side chains with increased steric bulk compared to the native Gly(−1) residue, including D-amino acids, were found to compensate for the essential block B histidine in His73Ala mutants in the initial N–S acyl shift of the protein splicing pathway. In the case of the M86 intein, large (−1) side chains can even rescue protein splicing activity as a whole. With the comparison of three crystal structures, namely of the M86 intein as well as of its Gly(−1)Phe and Gly(−1)Phe/His73Ala mutants, our data supports a model in which the intein's active site can exert a strain by varying mechanisms on the different angles of the scissile bond at the extein–intein junction to effect a ground-state destabilization. The compensatory mechanism of the block B histidine is the first example for the direct functional role of an extein residue in protein splicing. It sheds new light on the extein–intein interplay and on possible consequences of their co-evolution as well as on the laboratory engineering of improved inteins.
2019-01-21T13:38:45Z
2019-01-21T13:38:45Z
2018-10-03
Article
2041-6520
2041-6539
10.1039/C8SC01074A
http://hdl.handle.net/10033/621664
Chemical Science
http://xlink.rsc.org/?DOI=C8SC01074A
Attribution-NonCommercial-ShareAlike 4.0 International
http://creativecommons.org/licenses/by-nc-sa/4.0/
Royal Society of Chemistry
10
1
239
251
Chemical Science
oai:repository.helmholtz-hzi.de:10033/6224872020-09-29T03:08:41Zcom_10033_620653col_10033_620654
Resolving Inflammation: Synthesis, Configurational Assignment, and Biological Evaluations of RvD1.
Tungen, Jørn Eivind
Gerstmann, Lisa
Vik, Anders
De Matteis, Roberta
Colas, Romain Alexandre
Dalli, Jesmond
Chiang, Nan
Serhan, Charles Nicholas
Kalesse, Markus
Hansen, Trond Vidar
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
Karstedt's catalyst
natural products
sp3-sp3 cross-coupling
specialized pro-resolving mediators
total synthesis
New drugs that can resolve inflammation without immunosuppressive effects are at the medicinal chemistry frontier. Pro-resolving endogenously formed small molecules, that is, the resolvins, are excellent candidates displaying such bioactions. The first total synthesis of the specialized pro-resolving mediator RvD1n-3 DPA has been achieved using the underutilized sp3 -sp3 Negishi cross coupling reaction and an alkyne hydrosilylation-protodesilylation protocol. Biological evaluations revealed that this novel mediator displays low nanomolar pro-resolving properties and potently activates the human DRV1/GPR32 receptor. As such, this endogenous natural product is a lead compound for the development of novel immunoresolvents.
2020-09-28T11:34:51Z
2020-09-28T11:34:51Z
2018-12-20
Article
Chemistry. 2019 Jan 28;25(6):1476-1480. doi: 10.1002/chem.201806029. Epub 2018 Dec 20.
30511787
10.1002/chem.201806029
http://hdl.handle.net/10033/622487
1521-3765
Chemistry (Weinheim an der Bergstrasse, Germany)
en
info:eu-repo/grantAgreement/H2020/677542
openAccess
Attribution-NonCommercial-ShareAlike 4.0 International
http://creativecommons.org/licenses/by-nc-sa/4.0/
Wiley
25
6
1476
1480
Chemistry (Weinheim an der Bergstrasse, Germany)
United States
United Kingdom
United Kingdom
Germany
oai:repository.helmholtz-hzi.de:10033/6224942020-10-02T01:44:25Zcom_10033_620653col_10033_620654
Desymmetrization of C -Symmetric Bis(Boronic Esters) by Zweifel Olefinations.
Linne, Yannick
Schönwald, Axel
Weißbach, Sebastian
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
C2-symmetry
desymmetrization
lithiation-borylation chemistry
mono-Zweifel olefination
natural product synthesis
anti-Configured 1,3-dimethyl deoxypropionate motifs are important sub structures in natural products. Herein, we describe a bidirectional approach for the rapid construction of natural products featuring such motifs by using C2 -symmetrical 1,3-bis(boronic esters). As for its application in convergent syntheses it was important to establish a selective mono-Zweifel olefination we describe the scope and limitations by using different 1,3-bis(boronic esters) and nucleophiles. This protocol takes advantage of the combination of the Hoppe-Matteson-Zweifel chemistry, which was elegantly put into practice by Aggarwal et al. In order to show its applicability the total syntheses of two natural products, serricornin and (+)-invictolide, were performed.
2020-10-01T14:17:55Z
2020-10-01T14:17:55Z
2020-06-03
Article
Chemistry. 2020 Jun 26;26(36):7998-8002. doi: 10.1002/chem.202000599.
32068298
10.1002/chem.202000599
http://hdl.handle.net/10033/622494
1521-3765
Chemistry (Weinheim an der Bergstrasse, Germany)
en
Attribution-NonCommercial-ShareAlike 4.0 International
http://creativecommons.org/licenses/by-nc-sa/4.0/
Wiley
26
36
7998
8002
Chemistry (Weinheim an der Bergstrasse, Germany)
Germany
oai:repository.helmholtz-hzi.de:10033/6226722021-01-13T01:37:54Zcom_10033_620653col_10033_620654
Total Synthesis and Structure Revision of Halioxepine.
Poock, Caroline
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
halo etherification
natural product synthesis
quaternary stereocenter
structure elucidation
terpenoids
The first total synthesis of halioxepine is accomplished using a 1,4-addition for constructing the quaternary center at C10 and a halo etherification for the generation of the tertiary ether at C7. The correct structure of halioxepine was determined by assembling different enantiomeric building blocks and by changing the relative configuration between C10 and C15.
2021-01-12T13:02:50Z
2021-01-12T13:02:50Z
2020-11-20
Article
Chemistry. 2020 Nov 20. doi: 10.1002/chem.202004847.
33215739
10.1002/chem.202004847
http://hdl.handle.net/10033/622672
1521-3765
Chemistry (Weinheim an der Bergstrasse, Germany)
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
Wiley
Chemistry (Weinheim an der Bergstrasse, Germany)
Germany
oai:repository.helmholtz-hzi.de:10033/6227092021-01-30T01:37:07Zcom_10033_620653com_10033_620618col_10033_620654col_10033_620619
Ribosome-Targeting Antibiotics Impair T Cell Effector Function and Ameliorate Autoimmunity by Blocking Mitochondrial Protein Synthesis.
Almeida, Luís
Dhillon-LaBrooy, Ayesha
Castro, Carla N
Adossa, Nigatu
Carriche, Guilhermina M
Guderian, Melanie
Lippens, Saskia
Dennerlein, Sven
Hesse, Christina
Lambrecht, Bart N
Berod, Luciana
Schauser, Leif
Blazar, Bruce R
Kalesse, Markus
Müller, Rolf
Moita, Luís F
Sparwasser, Tim
HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.;HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
Argyrin
Linezolid
NAD+
T cells
antibiotics
autoimmunity
elongation factor G1
mitochondria
mitochondrial translation
ribosome-targeting
While antibiotics are intended to specifically target bacteria, most are known to affect host cell physiology. In addition, some antibiotic classes are reported as immunosuppressive for reasons that remain unclear. Here, we show that Linezolid, a ribosomal-targeting antibiotic (RAbo), effectively blocked the course of a T cell-mediated autoimmune disease. Linezolid and other RAbos were strong inhibitors of T helper-17 cell effector function in vitro, showing that this effect was independent of their antibiotic activity. Perturbing mitochondrial translation in differentiating T cells, either with RAbos or through the inhibition of mitochondrial elongation factor G1 (mEF-G1) progressively compromised the integrity of the electron transport chain. Ultimately, this led to deficient oxidative phosphorylation, diminishing nicotinamide adenine dinucleotide concentrations and impairing cytokine production in differentiating T cells. In accordance, mice lacking mEF-G1 in T cells were protected from experimental autoimmune encephalomyelitis, demonstrating that this pathway is crucial in maintaining T cell function and pathogenicity.
2021-01-29T15:54:04Z
2021-01-29T15:54:04Z
2020-11-24
Article
Immunity. 2021 Jan 12;54(1):68-83.e6. doi: 10.1016/j.immuni.2020.11.001. Epub 2020 Nov 24.
33238133
10.1016/j.immuni.2020.11.001
http://hdl.handle.net/10033/622709
1097-4180
Immunity
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
Elsevier (Cell Press)
54
1
68
83.e6
Immunity
United States
United States
United States
oai:repository.helmholtz-hzi.de:10033/6228112021-04-01T01:31:01Zcom_10033_620653col_10033_620654
The Total Synthesis of Chondrochloren A.
Linne, Yannick
Bonandi, Elisa
Tabet, Christopher
Geldsetzer, Jan
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
1,2-metallate rearrangement
Hoppe anion
chondrochloren
natural product synthesis
polyketides
The first total synthesis of chondrochloren A is accomplished using a 1,2-metallate rearrangement addition as an alternative for the Nozaki-Hiyama-Kishi reaction. This transformation also avoids the inherent challenges of this polyketide segment and provides a new, unprecedented strategy to assemble polyketidal frameworks. The formation of the Z-enamide is accomplished using a Z-selective cross coupling of the corresponding amide to a Z-vinyl bromide.
2021-03-31T14:36:50Z
2021-03-31T14:36:50Z
2021-02-25
Article
Angew Chem Int Ed Engl. 2021 Mar 22;60(13):6938-6942. doi: 10.1002/anie.202016072. Epub 2021 Feb 25.
33450788
10.1002/anie.202016072
http://hdl.handle.net/10033/622811
1521-3773
Angewandte Chemie (International ed. in English)
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
Wiley-VCH
60
13
6938
6942
Angewandte Chemie (International ed. in English)
Germany
oai:repository.helmholtz-hzi.de:10033/6228762021-05-19T04:38:32Zcom_10033_620653col_10033_620654
Synthesis of Desepoxy-Tedanolide C.
Lücke, Daniel
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
Kiyooka aldol
polyketides
structure elucidation
tedanolie C
tertiary alcohol
The synthesis of desepoxy-tedanolide C was accomplished and provided experimental evidence on the configuration of tedanolide C. The reported chemical shifts and coupling constants point to a configuration different from the published structure and analogous to the structures of the other members of this family of natural products. The key step is a Kiyooka aldol protocol for the stereoselective synthesis of the tertiary alcohol flanked by three additional oxygenated carbon atoms. Furthermore, two additional aldol reactions and a Julia-Kocienski olefination were used to assemble the carbon framework.
2021-05-18T09:39:40Z
2021-05-18T09:39:40Z
2021-04-09
Article
Chemistry. 2021 Apr 26;27(24):7085-7089. doi: 10.1002/chem.202100553. Epub 2021 Apr 9.
33769622
10.1002/chem.202100553
http://hdl.handle.net/10033/622876
1521-3765
Chemistry (Weinheim an der Bergstrasse, Germany)
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
Wiley
27
24
7085
7089
Chemistry (Weinheim an der Bergstrasse, Germany)
Germany
oai:repository.helmholtz-hzi.de:10033/6230532021-10-01T02:15:46Zcom_10033_620653col_10033_620654
Recent Applications of the Diels-Alder Reaction in the Synthesis of Natural Products (2017-2020)
Sara, Alexandru A.
Um-E-Farwa, Um E.Farwa
Saeed, Aamer
Kalesse, Markus
HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.
cycloaddition
Diels-Alder reaction
natural products
recent advances
stereocontrol
total synthesis
The Diels-Alder reaction has long been established as an extremely useful procedure in the toolbox of natural product chemists. It tolerates a wide spectrum of building blocks of different complexity and degrees of derivatization, and enables the formation of six-membered rings with well-defined stereochemistry. In recent years, many total syntheses of natural products have been reported that rely, at some point, on the use of a [4+2]-cycloaddition step. Among classic approaches, several modifications of the Diels-Alder reaction, such as hetero-Diels-Alder reactions, dehydro-Diels-Alder reactions and domino-Diels-Alder reactions, have been employed to extend the scope of this process in the synthesis of natural products. Our short review covers applications of the Diels-Alder reaction in natural product syntheses between 2017 and 2020, as well as selected methodologies which are inspired by, or that can be used to access natural products. 1 Introduction 2 Syntheses from 2017 3 Syntheses from 2018 4 Syntheses from 2019 5 Syntheses from 2020 6 Conclusion. © 2021 Georg Thieme Verlag. All rights reserved
2021-09-30T10:07:26Z
2021-09-30T10:07:26Z
2021-06-21
Review
(2021) Synthesis (Germany), doi:10.1055/a-1532-4763.
00397881
10.1055/a-1532-4763
http://hdl.handle.net/10033/623053
1437210X
Synthesis (Germany)
2-s2.0-85112214577
SCOPUS_ID:85112214577
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
Thieme
Synthesis (Germany)
oai:repository.helmholtz-hzi.de:10033/6231862022-05-07T01:56:46Zcom_10033_620653col_10033_620654
Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment.
Geldsetzer, Jan
Kalesse, Markus
Z-enamide
cross coupling
myxobacteria
natural product
ribolactone
The stereoselective synthesis of the (Z)-enamide fragment of chondrochloren (1) is described. A Buchwald-type coupling between amide 3 and (Z)-bromide 4 was used to generate the required fragment. The employed amide 3 comprising three chiral centers was obtained through a seven-step sequence starting from ᴅ-ribonic acid-1,4-lactone. The (Z)-vinyl bromide 4 is accessible in four steps from 4-hydroxybenzaldehyde. The pivotal cross coupling between both fragments was achieved after extensive experimentation with copper(I) iodide, K2CO3 and N,N'-dimethylethane-1,2-diamine.
2022-05-06T13:25:39Z
2022-05-06T13:25:39Z
2020-04-14
2022-05-06
Article
1860-5397
32362944
10.3762/bjoc.16.64
http://hdl.handle.net/10033/623186
Beilstein journal of organic chemistry
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
16
670
673
Beilstein journal of organic chemistry
Germany
oai:repository.helmholtz-hzi.de:10033/6232292022-06-15T02:53:01Zcom_10033_620653col_10033_620654
Contiguous Quaternary Carbons: A Selection of Total Syntheses.
Eggert, Alina
Etling, Christoph
Lübken, Dennis
Saxarra, Marius
Kalesse, Markus
canataxpropellane
natural products
ortho-photo-cycloaddition
taxane diterpene
total synthesis
waihoensene
Contiguous quaternary carbons in terpene natural products remain a major challenge in total synthesis. Synthetic strategies to overcome this challenge will be a pivotal prerequisite to the medicinal application of natural products and their analogs or derivatives. In this review, we cover syntheses of natural products that exhibit a dense assembly of quaternary carbons and whose syntheses were uncompleted until recently. While discussing their syntheses, we not only cover the most recent total syntheses but also provide an update on the status quo of modern syntheses of complex natural products. Herein, we review (±)-canataxpropellane, (+)-waihoensene, (-)-illisimonin A and (±)-11-O-debenzoyltashironin as prominent examples of natural products bearing contiguous quaternary carbons.
2022-06-14T14:17:35Z
2022-06-14T14:17:35Z
2020-08-24
2020-07-22
Article
32847075
10.3390/molecules25173841
http://hdl.handle.net/10033/623229
1420-3049
Molecules (Basel, Switzerland)
en
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
25
17
Molecules (Basel, Switzerland)
Switzerland