Direkt zum Inhalt
Bannergrafik (Fb 15)
Sie sind hier:» Universität » Chemie » AG Koert
AK Koert - 2018

Bilder des Ehemaligentreffens


Research Areas:

Synthesis of Biologically Active Compounds
Synthetically Modified Ion Channels
Organic Molecules for Internal Interfaces

Synthesis of target structures and their associated target functions is a main goal of organic chemistry. We design and carry out multistep organic synthesis. Part of the work is the structural and functional analysis of the synthetic products. Selectivity is the key factor for synthetic efficiency. Therefore questions of chemo-, regio- and stereo-selectivity are always central to our research projects. One group of synthetic targets includes natural products of medicinal interest and enzyme inhibitors.



Ion channels perform key tasks in biological systems such as neuronal signaling, muscular control, and sensing. Malfunctions cause serveral serve or common diseases. We synthesize new membrane-bound ion channels for studying their function (charge transport) to understand the functionality. A derivatization leads to the control of key characteristics like selectivity, dwell times and gating.


Gramicidin crown ether
OmpF crown ether

Internal interfaces between two solids play an important role in modern materials science and their technological applications like novel solar cells, OFETs, OLEDs and biosensors.

We synthesize functionalized pentacene for studies of internal interfaces.

Surface modification



Latest NEWS:


Feb 2019 

Jan 2019

TOC Michel
A stereoselective synthetic approach to the natural product (+)-nivetetracyclate A is reported. The tetracyclic skeleton was assembled in a convergent manner by an alkylation to a diarylmethane and subsequent Friedel–Crafts acylation. Further key steps are an asymmetric Sharpless epoxidation and the boron trifluoride-mediated diastereoselective rearrangement of an epoxy alcohol to a β-hydroxy aldehyde. Optimized timing for the deprotection step and the chemo- and stereoselective Noyori-transfer hydrogenation of a 1,4-diketone allowed the late stage introduction of the C4 stereocenter.

Nov 2018


Adsorption of ethynyl-cyclopropyl-cyclooctyne (ECCO), an alkyne-functionalized cyclooctyne, on Si(001) was studied by means of X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Together, XPS and STM results clearly indicate chemoselective adsorption of ECCO on Si(001) via a [2+2] cycloaddition of the strained triple bond of cyclooctyne without reaction of the ethynyl group. The results are compared to the adsorption of acetylene on Si(001): C2H2 adsorbs on Si(001) via a precursor-mediated reaction channel as it was shown by means of temperature dependent measurements of the sticking probability as well as by means of STM experiments at variable temperature. On the other hand, cyclooctyne adsorbs on Si(001) via a direct reaction channel. This qualitative difference in the reaction pathways of the two functionalities leads to the observed chemoselective adsorption of ECCO via the strained triple bond of cyclooctyne. As the ethynyl group stays intact, monolayers of ECCO on Si(001) form a well defined interface between the silicon substrate and further organic molecular layers which can be attached to the ethynyl functionality.

Okt 2018



Disclosed herein is a visible light mediated cyclization of methyl (α‐naphthyl) acrylates and heteroaromatic analogues yielding substituted acenaphthenes and azaacenaphthenes. This highly functional‐group‐tolerant transformation was put to the test in an enantioselective formal synthesis of delavatine A. Mechanistic details were elucidated by DFT‐calculations revealing a novel intramolecular H‐transfer mediated by a primary amine. The generality of this transformation enables a novel synthetic strategy of five membered ring annulation at an advanced stage, allowing reliance upon naphthalene chemistry up to the point of acenaphthene construction.

Aug 2018

  • Josefine Kahlstatt, Philipp Reiß, Thomas Halbritter, Lars-Oliver Essen, Ulrich Koert,  Alexander Heckel " A light-triggered transmembrane porin", Chem. Comm., 2018, 9623-9626.



      Porins are ideal model systems for channel engineering. OmpG is a robust, monomeric, transmembrane b -barrel without ion selectivity. Here, we present a photocaged diethylaminocoumarin (DEACM) hybrid of OmpG. Blockage of the pore by DEACM is confirmed by reduced conductivity. An optimal effect was obtained when two bulky butyl-substituted coumarin cages were attached on the inside of the pore. Irradiation at 385 nm removed the photocages, leading to a restoration of channel conductivity



  The hydrofluorination of enolizable ynones with AgF in t-BuOH/DMF is reported. The formation of furans as side products can be suppressed using 2,2′-biphenol. The corresponding β-fluoroenones were obtained with good Z-selectivity. A variety of functional groups are tolerated. β-Fluoroenones are vinylogous acid fluorides whose hydrolysis to vinylogous acids can be avoided under the reported reaction conditions. The asymmetric 1,2-reduction of β-fluoroenones to 3-fluoroallylic alcohols is possible with pinacolborane and a Ni(0) catalyst prepared from a pyrimidyloxazoline ligand.

Feb 2018





An efficient stereoselective synthesis of the enantiomer of the benzodihydropentalene core of fijiolides A and B has been achieved. The asymmetric conjugate addition of styrylboronic acid to an indenone produced the first stereocenter. Ring C was installed by ring-closing metathesis of a cis disubstituted indanone. Regioselective epoxide opening by NaSePh and subsequent oxidative elimination produced an allylic alcohol. The final introduction of the cyclopentadiene was possible by elimination of an in situ formed triflate.

Nov 2017


schnorbert naturstoff 3 

A new C-glycosylflavone, apigenin 7-methyl ether 6-C-[beta-xylopyranosyl-(13)-beta-glucopyranoside]
named distemonanthoside was isolated from the stem bark of
Distemonanthus benthamianus Baill.,
Fabaceae, along with six known compounds, sitosterol 3-
O-beta-D-glucopyranoside, 4-methoxygallic acid,
syringic acid, quercetin, 6
-O-acetylvitexin, quercetin 3-O-beta-D-glucopyranoside. The structures of those
compounds and others were determined through spectral analyses. Compounds distemonanthoside,
sitosterol 3-
O-beta-D-glucopyranoside, 4-methoxygallic acid and quercetin were tested against a clinical isolate strain of Mycobacterium tuberculosis AC 45; they exhibited good to moderate antitubercular
activities with MIC values ranged from 31.25 to 125


Jan fridolin wagner ejoc

The use of cross-coupling reactions for the synthesis of methylene-bridged bisnaphthalenes bearing two nitro groups on one naphthalene and two amino groups on the other has been investigated. A Hauser-Heck reaction was used to prepare the substituted naphthalene building blocks. It was not possible to install a transmetallating function in the benzylic position due to side reactions with the nitro and the amino groups. A successful Suzuki reaction was achieved using naphthyl trifluoroborates and bromomethyl naphthalenes. The resulting dinaphthyl methanes could be useful for the synthesis of push-pull substituted pentacenes.

Aug 2017

  • "Rauvolfianine, a new antimycobacterial glyceroglycolipid and other constituents from Rauvolfia caffra. Sond (Apocynaceae)", Nat. Prod. Res. 2017, 1-6.



The chemical investigation of the extract of the dried leaves of Rauvolfia caffra (Sond) (synonym Rauvolfia macrophylla) (Apocynaceae) led to isolation of a new glycoside derivative, rauvolfianine (1) as well as six known compounds: oleanolic acid (2), sitosterol-3-O-β-D-glucopyranoside (3), betulinic acid (4), vellosimine (5), sarpagine (6) and D-fructofuranosyl-β-(2→1)-α-D-glucopyranoside (7). Compounds 1, 2, 3, 4 and 7 were evaluated for antitubercular activity. Compounds 1 and 2 were the most active (MIC = 7.8125 and 31.25 μg/mL) towards the Isoniazid resistant strain of Mycobacterium tuberculosis AC45. Their structures and relative stereochemistry were elucidated by spectroscopic methods.

Apr 2017

  • "A new procyanidin B from Campylospermum zenkeri (Ochnaceae) and antiplasmodial activity of two derivatives of (±)-serotobenine", Nat. Prod. Res. 2017, 2875-2884.

Norbert TOC klein

Phytochemical investigation of the stem bark of Campylospermum zenkeri led to the isolation of five known compounds: (Z,Z)-9,12-octadecadienoic acid (1), serotobenine (2), agathisflavone (3), lophirone A (4) and lophirone F (5), together with a new derivative of procyanidin B, a catechin dimer named zenkerinol (6). Serotobenine (2) is structurally related to decursivine which shows moderate activity against D6 and W2 strains of Plasmodium falciparum. For a better understanding of structure-activity relationships, three new semi-synthetic derivatives of serotobenine (2) have been prepared. These are: serotobenine monopropionate (2a), serotobenine monopivalate (2b) and serotobenine cyclohexyl ether (2c) respectively. Two of them (2a) and (2b), were evaluated for their antiplasmodial activity against P. falciparum 3D7 strain in a parasite lactate-dehydrogenase (pLDH) assay. Compound 2b was more active than compound 2a based on their IC50 values (36.6 and 123 μM, respectively).

Mrz 2017

Paul TOC real

The metal catalyzed cycloaddition of silyl nitronates and        nitriles leading to 1,2,4 oxadiazoles is described. AgOTf        and Yb(OTf)3 are suitable catalysts. A variety of functional    groups is tolerated in the nitrile. The reaction works well        for alkenyl and aryl silyl nitronates while the use of alkyl      silyl nitronates is less efficient.


Jan 2017

Tricarbonyl Lars

Methods for the regioselective alkylation, arylation and alkenylation of α,β-diketoesters using organozinc reagents are reported. Alkylation and arylation in α-position is possible using diorgano zinc compounds. Alkenylation can be achieved using mixed alkenyl-dineopentyl zincates.



Review Tricarbonyl

Due to their high density of functional groups vicinal tricarbonyl compounds are versatile building blocks for the synthesis of complex target molecules. Methods for their preparation and their use in stereoselective C C bond formations as well as for the synthesis of heteroaromatics are summarized for the period 2006-2016. Several examples for their applications in natural product synthesis are given (awajanomycin, cladoniamide, wailupemycin). 



Most commonly studied bacteria grow symmetrically and divide by binary fission, generating two siblings of equal morphology. An exception to this rule are budding bacteria, in which new offspring emerges de novo from a morphologically invariant mother cell. Although this mode of proliferation is widespread in diverse bacterial lineages, the underlying mechanisms are still incompletely understood. Here, we perform the first molecular-level analysis of growth and morphogenesis in the stalked budding alphaproteobacterium Hyphomonas neptunium. Peptidoglycan labeling shows that, in this species, buds originate from a stalk-like extension of the mother cell whose terminal segment is gradually remodeled into a new cell compartment. As a first step toward identifying the machinery mediating the budding process, we performed comprehensive mutational and localization studies of predicted peptidoglycan biosynthetic proteins in H. neptunium. These analyses identify factors that localize to distinct zones of dispersed and zonal growth, and they suggest a critical role of the MreB-controlled elongasome in cell morphogenesis. Collectively, our work shows that the mechanism of growth in H. neptunium is distinct from that in related, polarly growing members of the order Rhizobiales, setting the stage for in-depth analyses of the molecular principles regulating the fascinating developmental cycle of this species.

Oct 2016


Total syntheses: An efficient stereoselective synthetic approach to 7–20 oxa-bridged abietane type natural products is reported. Key steps are an asymmetric Mukaiyama aldol addition to construct the C3 stereocenter and an intramolecular organocatalyzed Stetter-type Michael addition followed by a Tishchenko reaction. An intramolecular lactone–enolate arylation delivers the tetracyclic skeleton. This synthetic strategy was applied for the first total synthesis of (+)-elevenol, an antihepatitis C active compound from Fluegga virosa, and the first total synthesis of (+)-przewalskin.




Selectivity by strain: Cyclooctyne derivatives with different functional groups are shown to react on Si(001) selectively via the strained cyclooctyne triple bond. This selectivity originates from the distinctly different adsorption dynamics of the separate functional groups: The cyclooctyne triple bond exhibits a direct adsorption pathway as opposed to the majority of other organic functional groups, which generally react on Si(001) via a metastable intermediate.


Aug 2016


Ethynylcyclooctynes and diazides were synthesized and applied for a chemoselective sequence of copper(I)-catalyzed azide–alkyne cycloadditions and strain-promoted azide–alkyne cycloadditions. Chemoselectivity within the reaction sequence was achieved by balancing three factors: Cu-catalysis/ring strain/steric shielding. A cholic acid derived triazide was subjected to the cycloaddition sequence as a model system for a layer-by-layer synthesis on surfaces.




Nov 2015


γ-Aryl-β-ketoesters can be prepared in one step from aryl bromides and bis(trimethylsilyl) enol ethers using catalytic amounts of Pd(dba)2/t-Bu3P and stoichiometric amounts of Bu3SnF. The wide range of γ-(hetero)aryl-β-ketoesters that can be obtained illustrate the scope and limitations of this novel Hauser-Heck combination. γ-Aryl-β-ketoesters with a 1,3-dioxane acetal in the ortho position can easily be transformed into the hydroxy naphthoate in very good yield. Aqueous formic acid at 65 °C provides optimal conditions for this deprotective aromatization.

Oct 2015



α-Bromosulfones have been synthesized diastereoselectively by reaction of β-hydroxy-gem-dibromides with aromatic sulfinates. More sterical demanding groups in the β-position lead to increased stereoselectivity in these SN2-reactions. The lithiated α‑bromosulfones react diastereoselectively with alkylating agents, aldehydes and ketones. No configurational stability of the lithiated α‑bromosulfones was observed, but a fast equilibration towards a chelate-stabilized intermediate. Treatment of the α-bromosulfone with methylcuprate resulted in the substitution of the bromine by a methyl group.

Jul 2015


Distinct dipoles: New non-symmetrical fluoro-substituted pentacene derivatives are synthesized which feature distinct molecular dipoles. All compounds are analyzed regarding their optoelectronic and structural properties as isolated molecules and in thin solid films. A precise comparison between the moelcular and solid-state properties allows detailed insights into the exciton binding energies.

Jun 2015

ketol rearrangement

The stereospecific BF3-mediated α-ketol rearrangement of β-hydroxy-α-ketoamides yields isolable difluoroboranyloxy-3-keto-amides. The air-stable boron complexes exhibit novel reactivity in bromination and dipolar cycloaddition reactions.

Feb 2015


Et2O auf Si

The adsorption of diethyl ether (Et2O) on Si(001) was studied by means of scanning tunneling  microscopy (STM) and photoelectron spectroscopy. Et2O reacts on Si(001) via a datively bonded intermediate, which was isolated at surface temperatures below 100 K. At higher surface temperature, Et2O converts dissociatively into the final state by  cleaving one O−C bond; the resulting −O−C2H5 and −C2H5 fragments are found to attach on two Si dimers of neighboring dimer rows. Tipinduced hopping of the −C2H5 fragment on one dimer was observed at positive sample bias.


Sep 2014


The adsorption of diethyl ether (Et2O) on Si(001) was studied by means of scanning tunneling  microscopy (STM) and photoelectron spectroscopy. Et2O reacts on Si(001) via a datively bonded intermediate, which was isolated at surface temperatures below 100 K. At higher surface temperature, Et2O converts dissociatively into the final state by cleaving one O−C bond; the resulting −O−C2H5 and −C2H5 fragments are found to attach on two Si dimers of neighboring dimer rows. Tipinduced hopping of the −C2H5 fragment on one dimer was observed at positive sample bias.

Jun 2014


An efficient total synthesis of isoquinocyclinone was achieved using a pentacyclic lactone as key intermediate. The pyrrolo-pyrrole substructure was elaborated by acetylide acylation, conversion of an O,O-acetal into an N,O-acetal and intramolecular amidine alkylation.

May 2014


The enantioselective addition of indoles to mesoxalic ester amides is investigated. The feasibility of these vic-tricarbonyl compounds as building blocks in natural product synthesis is shown in the syntheses of cladoniamide G and F. They involve the arylation of mesoxalic ester amide, a Suzuki cross-coupling to a 2,2'-biindole and an intramolecular lactam formation as key steps.

Feb 2014


A synthesis of the 9-epimer of the marine natural product wailupemycin A is reported. The key reaction sequence consists of a diastereoselective enamine addition to a tricarbonyl monohydrate, the formation of an enol silyl acetal, and finally the stereocontrolled addition of the α-pyrone substructure.

Oct 2013


vic-Diketoamides react with a variety of isonitriles and carboxylic acids in a regioselective Passerini three-component reaction to give good to excellent yields of α-Acyloxy-β-keto-carboxamides. In case of Passerini reactions with electron withdrawing group-substituted acetic acids, a one pot Passerini-Knoevenagel reaction was accomplished by addition of triethylamine to produce 5-oxofuran-2,2(5H)-dicarboxamides in good to very good yields.

Aug 2013

  • Start of the Collaborative Research Centre "Structure and Dynamics of Internal Interfaces" (SFB 1083).


The Collaborative Research Centre SFB 1083 of the German DFG has been established at Philipps-Universität Marburg in collaboration with the Donostia International Physics Center (DIPC), San Sebastián, Spain. The aim is to achieve a detailed microscopic understanding of the chemical bonding, the electronic coupling, and the dynamics of energy transfer for model systems of different classes of hetero-interfaces.

Our group synthesize pentacene derivatives and functionalized cyclooctynes as molecular building blocks for organic interfaces.


Mar 2013


A total synthesis of the proposed structures of fulicineroside and its aglycone fulicinerine is reported. Comparison with the reported data for the natural product and the aglycone suggests a misassignment of the natural product's structure.



Jan 2013


Adsorption of cyclooctyne on Si(001) was investigated by means of scanning tunneling microscopy. Two different adsorption configurations were identified for the chemisorbed molecules which exhibit a tendency for clustering along the dimer rows. Our results suggest a direct adsorption pathway for cyclooctyne on Si(001) most likely governed by the molecule’s triple bond in combination with its high ringstrain.









6,13‑Disubstituted pentacenes were synthesized. Their electrochemical and optical properties and their solid-state packing motif were determined. 6,13‑Bis(trifluoromethyl)pentacene and 6,13‑dimethoxypentacene exhibit slipped face to face pi-stacking in the solid state while 6,13‑diethoxypentacene forms pairs of pi-stacking molecules in the solid state.




Crotylboration of vic-diketoamides and vic-diketo esters was achieved with high diastereoselectivity and complementary regioselectivity. Whereas (E)-crotylboration of α,β-diketoamides resulted in high yields (91–99%) of β-crotylated products obtained as a single diastereomer (anti), Lewis acid promoted crotylboration of α,β-diketo esters yielded the α-crotylated species with the anti product as main diastereomer.


Zuletzt aktualisiert: 13.03.2019 · schwabe4

Fb. 15 - Chemie

Arbeitsgruppe Koert, Hans-Meerwein-Straße 4, 35032 Marburg
Tel. +49 6421 28-26970, Fax +49 6421 28-25677, E-Mail: koert@chemie.uni-marburg.de

URL dieser Seite: https://www.uni-marburg.de/fb15/ag-koert

Impressum | Datenschutz