Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-60598 Wissenschaftlicher Artikel Riemer, Nastja; Riemer, Martin; Krüger, Mandy; Clarkson, Guy J.; Shipman, Michael; Schmidt, Bernd Synthesis of arylidene-beta-lactams via exo-selective Matsuda-Heck arylation of methylene-beta-lactams exo-Methylene-beta-lactams were synthesized in two steps from commercially available 3-bromo-2-(bromomethyl)-propionic acid and reacted with arene diazonium salts in a Heck-type arylation in the presence of catalytic amounts of Pd(OAc)(2) under ligand-free conditions. The products, arylidene-beta-lactams, were obtained in high yields as single isomers. The beta-hydride elimination step of the Pd-catalyzed coupling reaction proceeds with high exo-regioselectivity and E-stereoselectivity. With aryl iodides, triflates, or bromides, the coupling products were isolated only in low yields, due to extensive decomposition of the starting material at elevated temperatures. This underlines that arene diazonium salts can be superior arylating reagents in Heck-type reactions and yield coupling products in synthetically useful yields and selectivities when conventional conditions fail. Washington American Chemical Society 2021 11 The journal of organic chemistry : JOC 86 13 8786 8796 10.1021/acs.joc.1c00638 Institut für Chemie OPUS4-55254 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin Microwave-Promoted Pd-Catalyzed Synthesis of Dibenzofurans from Ortho-Arylphenols ortho-Aryl phenols, synthesized via protecting group free Suzuki-Miyaura coupling of ortho-halophenols and arene boronic acids, undergo a cyclization to dibenzofurans via oxidative C-H activation. The reaction proceeds under microwave irradiation in short reaction times using catalytic amounts of Pd(OAc)(2) without additional ligands. Hoboken Wiley 2017 11 Journal of Heterocyclic Chemistry 54 2 1287 1297 10.1002/jhet.2704 Institut für Chemie OPUS4-45896 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones). Stuttgart Thieme 2016 9 Synthesis 48 141 149 10.1055/s-0035-1560501 Institut für Chemie OPUS4-45398 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin Microwave-Promoted Deprenylation: Prenyl Ether as a Thermolabile Phenol Protecting Group para-Substituted aryl prenyl ethers undergo a deprenylation reaction upon microwave irradiation. This offers the opportunity to use a prenyl ether as a thermolabile protecting group in the synthesis of natural products with a chromone structure, which proceeds via a tandem deprenylation/6-endo-cyclization sequence. Stuttgart Thieme 2016 8 Synthesis 48 1399 1406 10.1055/s-0035-1561366 Institut für Chemie OPUS4-38878 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin Synthesis of Magnaldehydes B and E and Dictyobiphenyl B by Microwave-Promoted Cross-Coupling of Boronophenols Magnaldehydes B and E along with their 4'-methylated derivatives are naturally occurring 2,4'-biphenols that have been isolated from the Magnoliaceae. Herein, these natural products have been synthesized from a common intermediate, which was obtained by a microwave-promoted, hetero-geneously catalyzed, and protecting-group-free Suzuki-Miyaura coupling reaction in an aqueous medium. These reaction conditions were also successfully applied to a one-step synthesis of the slime mold metabolite dictyobiphenyl B. Weinheim Wiley-VCH 2015 7 European journal of organic chemistry 17 3760 3766 10.1002/ejoc.201500350 Institut für Chemie OPUS4-38398 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin; Schilde, Uwe Tandem Claisen Rearrangement/6-endo Cyclization Approach to Allylated and Prenylated Chromones Allyl, dimethylallyl and prenyl ethers derived from o-acyl-phenols reacted upon microwave irradiation to form C-allylated or -prenylated chromone derivatives, depending on the substitution pattern of the arene and the allyl substituent. The reaction proceeds through a tandem Claisen rearrangement and 6-endo-trig or 6-endo-dig cyclization sequence. For prenyl ethers, the tandem sequence can be extended by a Cope rearrangement to furnish 6-prenylchromones. The method is potentially useful for the synthesis of natural products and drugs. Weinheim Wiley-VCH 2015 10 European journal of organic chemistry 34 7602 7611 10.1002/ejoc.201501151 Institut für Chemie OPUS4-37859 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin Suzuki-Miyaura coupling of halophenols and phenol boronic acids: systematic investigation of positional isomer effects and conclusions for the synthesis of phytoalexins from Pyrinae The Suzuki-Miyaura couplings of o-, m-, and p-halophenols with o-, m-, and p-phenol boronic acids were investigated for all combinations under standardized conditions, using Pd/C as a heterogeneous catalyst and water as a solvent. In the case of iodophenols, conventional heating was used, while for bromophenols significantly better results could be obtained using microwave irradiation. This systematic study revealed that 2,4'-biphenol is particularly difficult to access, irrespective of the starting materials used, but that these difficulties can be overcome by using different additives. The conclusions drawn from this investigation allowed us to identify conditions for the protecting group-free or minimized total synthesis of biaryl-type phytoalexins. These compounds possess antibacterial activity and are produced by fruit trees as a response to microbial infection. Washington American Chemical Society 2014 15 The journal of organic chemistry 79 9 4104 4118 10.1021/jo500675a Institut für Chemie OPUS4-37347 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin; Schilde, Uwe Chroman-4-ones via microwave-promoted domino claisen rearrangement-oxa-michael addition: Synthesis of tabchromones A and B Allyl phenyl ethers with a pendant enone substituent undergo, upon microwave irradiation, a domino sequence of Claisen rearrangement and 6-endo-trig-cyclization to furnish functionalized chroman-4-ones. The natural products tabchromones A and B were synthesized via this method. Stuttgart Thieme 2014 4 Synlett : accounts and rapid communications in synthetic organic chemistry 25 20 2943 2946 10.1055/s-0034-1379364 Institut für Chemie OPUS4-34740 Wissenschaftlicher Artikel Schmidt, Bernd; Riemer, Martin; Karras, Manfred 2,2 '-Biphenols via protecting group-free thermal or microwave-accelerated suzuki-miyaura coupling in water User-friendly protocols for the protecting group-free synthesis of 2,2'-biphenols via Suzuki-Miyaura coupling of o-halophenols and o-boronophenol are presented. The reactions proceed in water in the presence of simple additives such as K2CO3, KOH, KF, or TBAF and with commercially available Pd/C as precatalyst. Expensive or laboriously synthesized ligands or other additives are not required. In the case of bromophenols, efficient rate acceleration and short reaction times were accomplished by microwave irradiation. Washington American Chemical Society 2013 9 The journal of organic chemistry 78 17 8680 8688 10.1021/jo401398n Institut für Chemie