TY - JOUR A1 - Schmidt, Bernd A1 - Nave, Stefan T1 - Stereoselective syntheses of enantiomerically pure 2,5-disubstituted dihydropyrans based on olefin metathesis JF - The journal of organic chemistry N2 - A short synthesis of 2,5-disubstituted dihydropyrans starting from D-mannitol as a chiral building block is described. Our synthetic approach combines ruthenium-catalyzed ring closing olefin metathesis and palladium-catalyzed nucleophilic substitution. Y1 - 2006 U6 - https://doi.org/10.1021/jo061190k SN - 0022-3263 VL - 71 IS - 19 SP - 7364 EP - 7369 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hermanns, Jolanda T1 - Ring closing metathesis of substrates containing more than two C-C-double bonds : rapid access to functionalized heterocycles N2 - In most cases where ring closing metathesis is applied to the synthesis of heterocycles, alpha,omega-dienes are used as precursors. If substrates containing more than two double bonds are subjected to a metathesis reaction, carba- or heterocycles bearing additional exocyclic alkene functionality result, or multiple ring closing processes occur. This offers interesting and potentially very useful synthetic perspectives. On the other hand, selectivity problems need to be addressed as the cyclization of substrates with more than two double bonds available for olefin metathesis may result in constitutional isomers or stereoisomers. This review highlights problems and opportunities evolving from ring closing metathesis of tri-, tetra-, and polyenes as a strategy for the selective synthesis of functionalized heterocycles. The chapter on RCM of trienes is subdivided according to the symmetry of the metathesis precursor. The following two chapters deal with the double or multiple RCM of tetra- or polyenes. These processes are further classified according to the preferred cyclization mode. Finally, the application of cascade or domino metathesis reactions to the synthesis of heterocycles will be discussed. These processes can be classified into those where exclusively C-C-double bonds take part in the metathesis reaction, and those where one or more C-C-triple bonds are involved Y1 - 2006 ER - TY - JOUR A1 - Schmidt, Bernd T1 - Olefin metathesis and isomerization : from undesired side reactions to useful synthetic methodology N2 - Conversion of ruthenium carbene complexes to ruthenium hydride complexes by organometallic transformations in situ opens up interesting synthetic perspectives. In this account the use of Grubbs' catalyst to synthesize pent-4- enals selectively from diallyl- and allyl homoallyl ethers and scope and limitations of a Tandem RCM-isomerization sequence for the synthesis of cyclic enol ethers are discussed. (c) 2006 Elsevier B.V. All rights reserved Y1 - 2006 UR - http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGM-4JT9C6D- 2&_user=1584062&_coverDate=07%2F19%2F2006&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_sea rchStr U6 - https://doi.org/10.1016/j.molcata.2006.03.026 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Nave, Stefan T1 - Control of ring size selectivity by substrate directable RCM N2 - Hydroxy groups may exert strong catalyst-directing effects in olefin metathesis reactions, which are exploited for a ring size-selective RCM reaction Y1 - 2006 UR - http://pubs.rsc.org/en/content/articlehtml/2006/cc/b604359c U6 - https://doi.org/10.1039/B604359c ER - TY - JOUR A1 - Schmidt, Bernd A1 - Nave, Stefan T1 - Palladium-catalyzed O-allylation of alpha-hydroxy carbonyl compounds N2 - alpha-Hydroxy carbonyl compounds undergo smooth O-allylation using allylic carbonates and Pd(0) catalysts. This method has significant advantages over other O-allylation methods as it provides a solution to several problems previously observed for this synthetic transformation Y1 - 2006 UR - http://onlinelibrary.wiley.com/doi/10.1002/adsc.200505361/pdf U6 - https://doi.org/10.1002/adsc.200505361 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia T1 - Unexpected transfer hydrogenation of C-C-double bonds during Tandem-RCM-isomerization reactions JF - Journal of organometallic chemistry N2 - Unexpected hydrogen transfer from 2-propanol to C-C-double bonds has been observed in the course of a Tandem RCM-isomerization reaction leading to sterically congested spirocycles. KW - ruthenium KW - metathesis KW - isomerization KW - hydrogenation KW - transferhydrogenation KW - tandem sequence Y1 - 2006 U6 - https://doi.org/10.1016/j.jorganchem.2006.07.011 SN - 0022-328X VL - 691 IS - 24-25 SP - 5218 EP - 5221 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia T1 - Ring-size-selective enyne metathesis as a tool for desymmetrization of an enantiopure C-2-symmetric building block N2 - The enantiomerically pure C-2-syrnmetrical hexa-1,5-diene-3,4-diol is selectively monopropargylated. The products undergo ring-closing enyne metathesis to give exclusively dihydropyrans as single stereoisomers. An unprotected hydroxy group is identified as the factor controlling the ring-size selectivity. Y1 - 2009 UR - http://pubs.acs.org/journal/joceah U6 - https://doi.org/10.1021/Jo9018649 SN - 0022-3263 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hoelter, Frank T1 - A stereodivergent synthesis of all stereoisomers of centrolobine : control of selectivity by a protecting-group manipulation N2 - All stereoisomers of the natural product centrolobine are selectively synthesized, by starting from a common precursor. Key steps are an enantioselective allylation with enantiomerically pure allylsilanes, a tandem ring-closing metathesis-isomerization reaction, and a Heck reaction by using an arene diazonium salt. By choosing appropriate conditions for the final deprotection step, either the cis-configured centrolobines or their epimers are selectively obtained. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200902053 SN - 0947-6539 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Werner, Frank A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - The reaction of 3,4-dihydro-2H-pyran with oxalyl chloride : formation and crystal structure analysis of an unexpected bicyclic product N2 - 3,4-Dihydro-2-H-pyran and oxalyl chloride react, depending on the conditions, to keto esters, a pyran-3- carboxylic acid or derivatives thereof, or to an hitherto unknown bicyclic acetal containing a vinyl chloride moiety. The structure of the latter product has been unambiguously elucidated by single-crystal X-ray structure analysis. A mechanism for its formation is proposed. Y1 - 2010 UR - 1960 = dx.doi.org/10.1002/jhet.456 SN - 0022-152X ER - TY - JOUR A1 - Schmidt, Bernd A1 - Berger, René A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Pd-Catalyzed [2+2+1] coupling of alkynes and arenes phenol diazonium salts as mechanistic trapdoors JF - Chemistry - a European journal N2 - Alkynes and phenol diazonium salts undergo a Pd-catalyzed [2+2+1] cyclization reaction to spiro[4,5]decatetraene-7-ones. This structure was confirmed for one example by X-ray single-crystal structure analysis. The reaction is believed to proceed through oxidative addition of the phenol diazonium cation to Pd(0), subsequent insertion of two alkynes, followed by irreversible spirocyclization. KW - alkynes KW - diazo compounds KW - palladium KW - phenols KW - spirocycles Y1 - 2011 U6 - https://doi.org/10.1002/chem.201100609 SN - 0947-6539 VL - 17 IS - 25 SP - 7032 EP - 7040 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Schmidt, Bernd A1 - Geissler, Diana T1 - Olefin-Metathesis-Based Synthesis of Furans by an RCM/Deprotonation/Phosphorylation Sequence and Their Diels-Alder Reactions JF - European journal of organic chemistry N2 - Butenolides, obtained by ring-closing metathesis (RCM) of acrylates, undergo quantitative deprotonation with amide bases. Trapping of the resulting anions with electrophiles, for example, chlorophosphates, give furans. Subsequent DielsAlder reaction and acid-catalysed rearrangement of the resulting oxabicyclonorbornadienes give substituted benzenes. KW - Lactones KW - Metathesis KW - Ruthenium KW - Oxygen heterocycles KW - Metalation Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201101078 SN - 1434-193X IS - 35 SP - 7140 EP - 7147 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Reznichenko, Alexander L. A1 - Emge, Thomas J. A1 - Audoersch, Stephan A1 - Klauber, Eric G. A1 - Hultzsch, Kai C. A1 - Schmidt, Bernd T1 - Group 5 metal binaphtholate complexes for catalytic asymmetric hydroaminoalkylation and hydroamination/cyclization JF - Organometallics N2 - 3,3'-Silylated binaphtholate tantalum and niobium complexes were shown to be efficient catalysts for the asymmetric hydroaminoalkylation of N-methylaniline derivatives and N-benzylmethylamine with simple alkenes in enantioselectivities of up to 80% ee. No hydroaminoalkylation was observed with aminoalkenes; rather, exclusive asymmetric hydroamination/cyclization took place in up to 81% ee. Y1 - 2011 U6 - https://doi.org/10.1021/om1011006 SN - 0276-7333 VL - 30 IS - 5 SP - 921 EP - 924 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Geissler, Diana T1 - Ru- and Pd-Catalysed Synthesis of 2-Arylfurans by One-Flask Heck Arylation/Oxidation JF - European journal of organic chemistry N2 - 2,5-Disubstituted furans were synthesized by one-flask Heck arylation/oxidation sequences. The starting materials are 2-substituted 2,3-dihydrofurans, conveniently available by RCM/isomerization sequences, and arenediazonium salts. These react in ligand-free Heck reactions to afford 2,5-disub-stituted 2,5-dihydrofurans, which are oxidized to the corresponding furans without isolation or intermediate workup. The oxidation is conveniently achieved with chloranil or DDQ, depending on the substrate. KW - Diazonium salts KW - Palladium KW - C-C coupling KW - Heck coupling KW - Furans KW - Oxidation KW - Oxygen heterocycles Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201100549 SN - 1434-193X IS - 25 SP - 4814 EP - 4822 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - A Cross-Metathesis-Conjugate addition route to enantiopure gamma-Butyrolactams and gamma-Lactones from a C-2-Symmetric Precursor JF - European journal of organic chemistry N2 - A protected derivative of (3R, 4R)-hexa-1,5-diene-3,4-diol, a conveniently accessible C-2-symmetric building block, undergoes single or double cross metathesis with methyl acryl-ate. The cross metathesis products are amenable to stereoselective conjugate addition reactions and can be converted into either gamma-butyrolactones or gamma-lactams. KW - Lactams KW - Lactones KW - Oxygen heterocycles KW - Metathesis KW - Desymmetrization Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201001528 SN - 1434-193X IS - 9 SP - 1721 EP - 1727 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hölter, Frank T1 - Suzuki-Miyaura cross coupling reactions with Phenoldiazonium salts JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - The Suzuki-Miyaura coupling of phenol diazonium salts and aryl trifluoroborates yields 4-hydroxybiaryls in a protecting group-free synthesis. Y1 - 2011 U6 - https://doi.org/10.1039/c1ob05256j SN - 1477-0520 VL - 9 IS - 13 SP - 4914 EP - 4920 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan T1 - A single precatalyst tandem RCM-allylic oxidation sequence JF - Chemical communications N2 - Ring closing metathesis of allyloxy styrenes and a subsequent Ru-catalyzed allylic oxidation can be combined to a tandem sequence that makes coumarins accessible using less active but more conveniently available first generation catalysts. Y1 - 2011 U6 - https://doi.org/10.1039/c1cc11347j SN - 1359-7345 VL - 47 IS - 20 SP - 5879 EP - 5881 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Synthesis of 8-Aryl-Substituted Coumarins based on Ring-Closing Metathesis and Suzuki-Miyaura coupling - synthesis of a Furyl Coumarin natural product from Galipea panamensis JF - The journal of organic chemistry N2 - The synthesis of 7-methoxy-8-(4-methyl-3-furyl)-2H-chromen-2-one, a natural product with antileishmanial activity recently isolated from the plant Galipea panamensis, is described. The key step is a Suzuki-Miyaura coupling of a furan-3-boronic acid and an 8-halocoumarin, which is advantageously synthesized using a ring-closing metathesis reaction. Several non-natural analogues are also available along these lines. Y1 - 2012 U6 - https://doi.org/10.1021/jo2026564 SN - 0022-3263 VL - 77 IS - 5 SP - 2360 EP - 2367 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - alpha,beta-Unsaturated delta-Valerolactones through RCM-Isomerization Sequence JF - Synlett : accounts and rapid communications in synthetic organic chemistry N2 - alpha,beta-Unsaturated d-lactones are accessible via a sequential ring-closing metathesis (RCM) double-bond migration reaction starting from butenoates of allyl alcohols. This approach proceeds efficiently with lower catalyst loadings and higher initial substrate concentrations compared to the alternative RCM of acrylates derived from homoallylic alcohols. KW - ruthenium KW - lactones KW - tandem reactions KW - metathesis KW - esters Y1 - 2012 U6 - https://doi.org/10.1055/s-0031-1290488 SN - 0936-5214 IS - 6 SP - 851 EP - 854 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan A1 - Jablowski, Eric T1 - Assisted tandem catalytic RCM-aromatization in the synthesis of pyrroles and furans JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - An assisted tandem catalytic transformation of diallyl amines and diallyl ethers into N-aryl pyrroles and furans, respectively, is described. The sequence relies on ring closing metathesis followed by dehydrogenation of the initially formed dihydropyrroles and dihydrofurans. Both steps are Ru-catalyzed, but the sequence requires only one precatalyst, because conversion of the metathesis catalyst into the dehydrogenation catalyst is achieved in situ, triggered by the oxidant tert-butyl hydroperoxide. Y1 - 2012 U6 - https://doi.org/10.1039/c2ob25543j SN - 1477-0520 VL - 10 IS - 26 SP - 5119 EP - 5130 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Elizarov, Nelli T1 - Selective arene functionalization through sequential oxidative and non-oxidative Heck reactions JF - Chemical communications N2 - A sequence of acetamide directed oxidative Heck reaction and deacetylation-diazotation-Heck coupling allows the traceless removal of the acetamide group and its dual exploitation as a catalyst directing group and a leaving group. Y1 - 2012 U6 - https://doi.org/10.1039/c2cc30752a SN - 1359-7345 VL - 48 IS - 36 SP - 4350 EP - 4352 PB - Royal Society of Chemistry CY - Cambridge ER -