Divergent Synthesis of 5,7-Diazaullazines Derivatives through a Combination of Cycloisomerization with Povarov or Alkyne-Carbonyl Metathesis

Ullazines and their π-expanded derivatives have gained much attention as active components in various applications, such as in organic photovoltaic cells or as photosensitizers for CO2 photoreduction. Here, we report the divergent synthesis of functionalized diazaullazines by means of two different domino-reactions consisting of either a Povarov/cycloisomerization or alkyne-carbonyl metathesis/cycloisomerization protocol. The corresponding quinolino-diazaullazine and benzoyl-diazaullazine derivatives were obtained in moderate to good yields. Their optical and electronic properties were studied and compared to related, literature-known compounds to obtain insights into the impact of nitrogen doping and π-expansion.

Synthesis and properties of 6-alkynyl-5-aryluracils

The development of a new and straightforward chemoselective method for the synthesis of uracil-based structures by combining Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling is reported. The methodology was applied to synthesize a series of novel compounds. The tolerance of the combination of different functional groups was tested. The influence of different functional groups on the physical properties was studied by ultraviolet-visible (UV-vis) and fluorescence spectroscopy, providing new insights into the potential applications of uracil-based structures.

π-Expanded azaullazines: synthesis of quinolino-azaullazines by Povarov reaction and cycloisomerisation

Doping and extension of polycyclic aromatic hydrocarbons (PAHs) by simple and efficient synthetic methods is of increased demand for the development of novel and improved organic electronics. Diarylindolizino[6,5,4,3-ija]quinolino[2,3-c][1,6]naphthyridines (quinolino-azaullazines) were prepared by combination of Pd catalyzed cross-coupling with Povarov and cycloisomerisation reactions. The products contain an electron-rich ullazine and an electron-poor quinoline moiety and show intramolecular charge transfer properties that can be tuned by the substitution pattern. The optical properties were studied experimentally and further elaborated by (TD)DFT calculations.

Synthesis and Properties of 5,7-Diazaullazines

Hitherto unknown 5,8-substituted-pyrimido[4,5,6-ij]pyrrolo[2,1,5-de]quinolizines (5,7-diazaullazines) were prepared by a three-step synthesis via Clauson-Kaas, Sonogashira, and cycloisomerization reactions with diverse functionalization. The properties, including cyclovoltammetry and UV-vis and fluorescence spectroscopy, as well as solvatochromism, were studied for selected derivatives and supported by density functional theory calculations. Results were compared in detail with previously reported 5- and 6-azaullazines, and the impact of introduced nitrogen atoms was analyzed.

Synthesis and Properties of 4- and 10-Benzoyl-1-azapyrenes

A series of 4- and 10-benzoyl-1-azapyrenes were prepared by a combination of Pd-catalyzed cross-coupling reactions and Brønsted-acid-mediated alkyne-carbonyl-metathesis (ACM). The photophysical and electrochemical properties of the products were studied and compared to theoretical results.

Dibenzoindolo[1,8]naphthyridines: Synthesis and Characterization of X-Shaped Aza[4,6]helicenes

This report describes a one-pot multi-step procedure to obtain double azahelicenes via nucleophilic fluorine substitution of 2,2-di(2-bromophenyl)-1,1-difluoroalkenes and palladium-catalysed ring closing reaction. The developed synthesis approach allows easy diversification of substituents at all four fragments of the obtained X-shaped aza[4,6]helicene entity. Yields range from 20 % to 60 % among 12 product examples. X-ray single crystal analysis reveals formation of (P,P) and (M,M) enantiomer mixture of products. Optical and electrochemical properties of selected products were studied by performing UV/Vis absorption, photoluminescence and cyclic voltammetry measurements. Experimental results are supported by (TD)-DFT, NICS and NICS2BC calculations.

Exploring Thiazolopyridine AV25R: Unraveling of Biological Activities, Selective Anti-Cancer Properties and In Silico Target and Binding Prediction in Hematological Neoplasms

Thiazolopyridines are a highly relevant class of small molecules, which have previously shown a wide range of biological activities. Besides their anti-tubercular, anti-microbial and anti-viral activities, they also show anti-cancerogenic properties, and play a role as inhibitors of cancer-related proteins. Herein, the biological effects of the thiazolopyridine AV25R, a novel small molecule with unknown biological effects, were characterized. Screening of a set of lymphoma (SUP-T1, SU-DHL-4) and B- acute leukemia cell lines (RS4;11, SEM) revealed highly selective effects of AV25R. The selective anti-proliferative and metabolism-modulating effects were observed in vitro for the B-ALL cell line RS4;11. Further, we were able to detect severe morphological changes and the induction of apoptosis. Gene expression analysis identified a large number of differentially expressed genes after AV25R exposure and significant differentially regulated cancer-related signaling pathways, such as VEGFA-VEGFR2 signaling and the EGF/EGFR pathway. Structure-based pharmacophore screening approaches using in silico modeling identified potential biological AV25R targets. Our results indicate that AV25R binds with several proteins known to regulate cell proliferation and tumor progression, such as FECH, MAP11, EGFR, TGFBR1 and MDM2. The molecular docking analyses indicates that AV25R has a higher binding affinity compared to many of the experimentally validated small molecule inhibitors of these targets. Thus, here we present in vitro and in silico analyses which characterize, for the first time, the molecular acting mechanism of AV25R, including cellular and molecular biologic effects. Additionally, this predicted the target binding of the molecule, revealing a high affinity to cancer-related proteins and, thus, classified AVR25 for targeted intervention approaches.

Pyrene-bridged acenaphthenes: synthesis and properties of a diacenaphtho[1,2-e:1',2'-l]pyrene and its symmetrical nitrogen analogue

The considerable need for novel polyaromatic hydrocarbons (PAHs) for applications in the area of organic electronics remains unchanged. Diacenaphthopyrene represents a new PAH consisting of two acenaphthylene units connected by a pyrene bridge. The system is built up by Pd-catalyzed cross-coupling, followed by acid catalyzed cyclosiomerization to generate the pyrene moiety. The new fused scaffold is formed in the last step in convincing yields by means of CH-activation. We additionally synthesized one aza-pyrene based analogue. The two hitherto unknown PAHs were investigated in detail by UV-Vis and PL spectroscopy, CV measurements and DFT calculations. Based on these results, the abilities of the novel structure as well as the effect of incorporation of nitrogen were evaluated.

Synthesis and Properties of Carbo- and Heterocyclic Benz[a]azulenes

A new and convenient synthesis of aryl-substituted naphtho[2,1-a]azulenes by the combination of Suzuki-Miyaura, Sonogashira, and cycloisomerization reactions is reported. The methodology was applied to the synthesis of hitherto unknown azuleno[1,2-h]quinolines, cyclohepta[1,2]indeno[4,5-b]thiophenes, and cyclohepta[1,2]indeno[4,5-c]thiophenes. The impact of different fused-heterocyclic rings on the photophysical and electrochemical properties of these azulene derivatives was studied by experimental and theoretical methods and hence provides a rationale for the preparation of novel azulene derivatives with improved properties for application as organic materials.

Synthesis and Properties of 5-Azaullazines

5-Azaullazines, indolizino[6,5,4,3-ija][1,5]naphthyridines, and their benzo-fused analogues were prepared in three steps by combination of Pd catalyzed cross-coupling reactions with Brønsted acid mediated cycloisomerisations. The reaction tolerates various substitution patterns and functional groups and proceeds in high yields. Optical and electrochemical properties of selected products were studied experimentally and by DFT calculations.

Synthesis and Properties of Benzo[h]imidazo[1,2-a]quinolines and 1,2a-Diazadibenzo[cd,f]azulenes

Benzo[h]imidazo[1,2-a]quinolines and 1,2a-diazadibenzo[cd,f]azulenes were prepared from a common intermediate by regioselective cycloisomerization reactions. The selectivity was controlled by the choice of Brønsted acid and solvent. The optical and electrochemical properties of the products were studied by UV/vis, fluorescence, and cyclovoltammetric measurements. The experimental results were complemented by density functional theory calculations.

Synthesis and Properties of Thieno[2',3',4':4,5]naphtho[1,8-cd]pyridines

Thieno[2',3',4':4,5]naphtho[1,8-cd]pyridines, S,N-doped pyrene analogs, were prepared by combination of Pd catalyzed cross-coupling reactions and acid-mediated cycloisomerization. The modular scope of the synthesis allowed for access to a variety of functionalized derivatives. The photophysical properties have been studied in detail by steady-state and femtosecond transient absorption accompanied by cyclic voltammetry and (TD)-DFT calculations. The introduction of a five-membered thiophene into the 2-azapyrene scaffold leads to redshifted emission and substantial effects on the excited state dynamics, e.g., quantum yield, lifetime, decay rates, and the ISC ability, which can be further tuned by the substitution pattern of the heterocyclic scaffold.

Dibenzoacridines: synthesis by alkyne-carbonyl-metathesis and properties

Dibenzo[a,j]acridines and regioisomeric dibenzo[c,h]acridines were synthesized from a common starting material, 2,3,5,6-tetrachloropyridine, by combination of site-selective cross-coupling reaction followed by ring-closing alkyne-carbonyl metathesis using simple Brønsted acids. The two regioisomeric series were accessed by change of the order of Sonogashira and Suzuki-Miyaura reactions. The optical properties of the products were studied by steady-state absorption spectroscopy and time-resolved emission measurements. The electronic properties of the products were further elucidated by DFT calculations.

Thienoindolizines and their Benzo-Fused Derivatives: Synthesis and Physical Properties

A series of thienoindolizine structural isomers have been synthesized in a one-pot, two-step procedure starting from easily accessible gem-difluoroalkene functionalized bromothiophenes. The developed method gives easy access to a range of thienoindolizine products containing thieno[3,2-g]-, thieno[3,4-g]- and thieno[2,3-g]indolizine core structures. The described synthesis strategy consists of a base mediated, transition metal free nucleophilic substitution of fluorine atoms by nitrogen containing heterocycles followed by a Pd catalyzed intramolecular cyclization. A series of 22 final product examples has been obtained with yields ranging from 29% to 95%. UV/Vis absorption, fluorescence spectroscopy, fluorescence lifetime measurements and cyclic voltammetry were carried out with selected final products to evaluate structural effects on photophysical and electrochemical properties. (TD)DFT and NICS calculations were performed to provide insight into the electronic properties of the four core molecular structures.

Synthesis and Properties of Diphenylbenzo[j]naphtho[2,1,8-def][2,7]phenanthrolines

A series of hitherto unknown 5,14-diphenylbenzo[j]naphtho[2,1,8-def][2,7]phenanthrolines, containing a 5-azatetracene and a 2-azapyrene subunit, were prepared by combination of Pd-catalyzed cross-coupling reactions with a one-pot Povarov/cycloisomerization reaction. In the final key step four new bonds are formed in one step. The synthetic approach allows for a high degree of diversification of the heterocyclic core structure. The optical and electrochemical properties were studied experimentally and by DFT/TD-DFT and NICS calculations. Due to the presence of the 2-azapyrene subunit, the typical electronic nature and characteristics of the 5-azatetracene moiety are lost and the compounds are electronically and optically more related to 2-azapyrenes.

Der Übergabeprozess in der zentralen Notaufnahme – Konsentierung von Inhalten im Rahmen eines Delphi-Verfahrens

Hintergrund und Ziel der Arbeit

Für die Übergabe in der Notaufnahme – der Nahtstelle von prähospitaler zu klinischer Versorgung – stellen Merkhilfen („mnemonics“) das „Rückgrat“ für eine strukturierte Übermittlung von relevanten Informationen dar. In Deutschland existiert bis zum heutigen Tag keine Standardisierung bzw. konkrete Vorgabe, welche Merkhilfe zur Übergabe genutzt werden soll. Die vorliegende Untersuchung definiert erstmalig anhand eines strukturierten und mehrstufigen Konsentierungsprozesses (Delphi-Verfahren) von Experten (Mandatsträgern), welche Übergabeinhalte für erforderlich gehalten werden. Ziel dabei ist die Schaffung einer Grundlage zur Entwicklung einer bundeseinheitlichen Merkhilfe.

Methodik

Durchgeführt wurde ein Delphi-Verfahren, welches sich an den Regularien der Arbeitsgemeinschaft der wissenschaftlichen medizinischen Fachgesellschaften e. V. (AWMF) orientiert.

Ergebnisse

Im Rahmen des durchgeführten Delphi-Verfahrens konnte neben konkreten Inhalten der Merkhilfe auch deren Reihenfolge festgelegt werden. Übergabeinhalte wurden zu den Punkten Crew Resource Management (CRM) und Patientenidentifikation, Beschreibung der Notfallsituation, Notfallpriorität (ABCDE-Schema) und Vitalparameter, durchgeführte Maßnahmen, Anamnese, Zusammenfassung mit der Möglichkeit für Rückfragen durch das übernehmende Team sowie Zeitdauer definiert.

Diskussion

Die Ergebnisse der Arbeit bilden die evidenzbasierte Grundlage für die Entwicklung einer konkreten Merkhilfe („mnemonic“). Weitere Untersuchungen sollten sich nach Entwicklung einer geeigneten Merkhilfe darauf fokussieren, diese im Rahmen einer (prä-)klinischen Anwendungsstudie auf Praxistauglichkeit zu testen. Gleichzeitig sollte ein entsprechendes Schulungskonzept ausgearbeitet werden. Langfristig wird als Ziel eine bundesweit einheitliche Einführung angestrebt.

Synthesis of Spirocyclic Diindeno[1,2-b:2′,1′-d]thiophenes

Spirocyclic diindenothiophenes were prepared by cyclization of tosylhydrazones, readily available from ketones, with 3,4-dibromo-2,5-bis(2-bromphenyl)thiophene. For bicyclic ketones, the bis-spirocycles were formed with very good diastereoselectivity.

Perioperative use of antibiotics in full-thickness rectal biopsies for Hirschsprung’s disease

Background

There is no consensus on the use of perioperative antibiotic in full-thickness rectal biopsies (FTB) in children suspected for Hirschsprung disease. The primary objective of this study was to examine the effect of perioperative antibiotics on infectious and overall complications rate in FTB performed in children under the age of 1 year.

Methods

A retrospective chart review. Two time periods were compared—one with and one without the routine use of perioperative antibiotics. The treatment included cefuroxime 100 mg/kg and metronidazole 20 mg/kg administered intravenously at anesthesia induction followed by peroral administration of amoxicillin 50 mg/kg with Clavulanic acid 12.5 mg/kg three times a day t.i.d. for 3 days postoperative.

Results

In the group with perioperative antibiotics the infectious complications rate was 3.3% compared to 13.4% in the group without (p = 0.03) with fever as the most common. The overall complication rate was 11.3% and 15.2%, respectively (p = 0.43).

Conclusion

Perioperative antibiotics significantly reduced the rate of infectious complications, but not the rate of overall complication rate after a full thickness rectal biopsy in children under the age of 1 year.

Synthesis and Properties of 1-Azapyrenes

A straightforward method for the synthesis of a series of hitherto unknown 1-azapyrenes is reported, which relies on a combination of Pd-catalyzed cross-coupling reactions with Brønsted acid-mediated cycloisomerization reactions. The methodology is highly modular and allows an efficient synthesis of various substituted products in high yields. The structural, electrochemical, and photophysical properties of 1-azapyrenes have been studied by ultraviolet-visible (UV-vis) and fluorescence spectroscopies, cyclic voltammetry, and density functional theory (DFT) calculations.

Regioselective Synthesis of Naphthothiophenes by Pd Catalyzed Cross-Coupling Reactions and Alkyne-Carbonyl Metathesis

Naphthothiophenes were prepared from commercially available 2,3-dibromothiophenes in two steps by one-pot Suzuki/Sonogashira or Sonogashira/Suzuki coupling reactions, followed by intramolecular alkyne-carbonyl-metathesis reactions. The final cyclization reaction proceeds in the presence of p-toluenesulfonic acid and provides a rapid access to two series of isomeric naphthothiophenes.

Synthesis of imidazo[1,2-a]benzoazepines by alkyne-carbonyl-metathesis

Imidazo[1,2-a]benzoazepines were prepared in good yields by combination of Pd catalyzed cross coupling reactions with alkyne-carbonyl metathesis (ACM).

Chemoenzymatic Asymmetric Synthesis of Pyridine-Based α-Fluorinated Secondary Alcohols

Fluoro‐substituted and heteroaromatic compounds are valuable intermediates for a variety of applications in pharma‐ and agrochemistry and synthetic chemistry. This study investigates the chemoenzymatic preparation of chiral alcohols bearing a heteroaromatic ring with an increasing degree of fluorination in α‐position. Starting from readily available picoline derivatives prochiral α‐halogenated acyl moieties were introduced with excellent selectivity and 64–95 % yield. The formed carbonyl group was subsequently reduced to the corresponding alcohols using the alcohol dehydrogenase from Lactobacillus kefir, yielding an enantiomeric excess of 95–>99 % and up to 98 % yield.

Synthesis of Dibenzotropones by Alkyne-Carbonyl Metathesis

Dibenzocycloheptanones (dibenzotropones) were prepared by Brønsted acid mediated intramolecular alkyne-carbonyl metathesis (ACM) reactions. The cyclization precursors are readily available by Sonogashira reaction of 2-bromobenzoyl chloride with terminal alkynes, followed by Suzuki reactions with benzaldehydes. The ACM reactions are highly modular and atom economic and allow for the construction of two regioisomeric series of dibenzotropones.

Synthesis of Pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by Alkyne-Carbonyl Metathesis

A concise and modular synthesis of pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds.

Synthesis of 2-Azapyrenes and Their Photophysical and Electrochemical Properties

A series of 5,7,9-substituted 2-azapyrenes were synthesized for the first time. The synthesis relies on Brønsted acid promoted benzannulation of alkyne precursors prepared by palladium-catalyzed cross-coupling reactions. The synthetic strategy is efficient and the scope covers a variety of functional groups. The electrochemical behavior and photophysical properties of the products were investigated by UV-vis and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations.

Synthesis of thieno[2,3-h]-/[3,2-h]quinolines and thieno[2,3-f] quinolines by Brønsted acid mediated cycloisomerisation

Several thieno[2,3-h]-/[3,2-h]- and [2,3-f]quinolines have been synthesised from 2,3-dihalogenated pyridines or -quinolines by site-selective Pd catalysed cross-coupling reactions and Brønsted acid mediated cycloisomerisations as the final key step. This newly developed synthetic strategy is used in a modular way to synthesize diverse regioisomeric derivatives, tolerates various functional groups, and proceeds with high selectivity, and the desired final products have been isolated in high overall yields.

Site-Selective Suzuki–Miyaura Reaction of 6,8-Dichloro-1,2,4-triazolo[4,3-a]pyridines

Triazolopyridines have found various applications as pharmaceuticals, agrochemicals, or optical materials. Consequently, the introduction of various functionalities at specific sites of this heterocyclic framework is of great importance. In this regard, we report the development of a site-selective Suzuki–Miyaura reactions leading to substituted triazolopyridines at positions 6 and 8. Under optimized conditions, the respective products have been obtained with high selectivity and yield.

Synthesis of 5- and 6-Azaindoles by Sequential Site-Selective Palladium-Catalyzed C–C and C–N Coupling Reactions

Two-step sequential procedures for the Pd-catalyzed synthesis of 5- and 6-azaindoles are reported. The reactions proceed in very good yields. 6-Azaindoles are formed through site-selective Pd-catalyzed Sonogashira reaction of 3,4-dibromopyridine with alkynes, followed by a Pd-catalyzed tandem C–N coupling and cyclization with amines. On the other hand, 5-azaindoles are obtained by a site-selective Pd-catalyzed C–N coupling reaction of 3,4-dibromopyridine with amines, followed by C–C coupling and cyclization with alkynes.

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

A two-step palladium-catalyzed procedure based on Suzuki–Miyaura cross coupling, followed by a double Buchwald–Hartwig reaction, allows for the synthesis of pharmaceutically relevant benzo[4,5]furo[3,2-b]indoles in moderate to very good yield. The synthesized compounds have been analyzed with regard to their inhibitory activity (IC₅₀) of nucleotide pyrophosphatases h-NPP1 and h-NPP3. The activity lies in the nanomolar range. The results were rationalized based on docking studies.

Synthesis of 1,3,4-Thiadiazolo[2′,3′:2,3]imidazo[4,5-b]indoles

Hitherto unknown thiadiazolo[2′,3′:2,3]imidazo[4,5-b]indoles were synthesized for the first time by base-mediated cyclocondensation, bromination, and subsequent cyclization by two-fold Buchwald–Hartwig reactions.

Synthesis of Acridones by Palladium-Catalyzed Buchwald–Hartwig Amination

The Buchwald–Hartwig amination allows an efficient and convenient synthesis of biologically and pharmaceutically important acridones by formation of a six-membered ring. With the described method, a number of derivatives have been synthesized in up to 95% yield by using a variety of anilines as well as benzylic and aliphatic amines.

Site-Selective Synthesis of 3,17-Diaryl-1,3,5,16-estratetraenes

A straightforward, site-selective arylation of the bis(triflate) of estrone by Suzuki–Miyaura reactions has been developed. Monoarylation occurs selectively at the D-ring with good to excellent yield. Such products were exemplarily employed for the synthesis of estrones containing two different aryl substituents.