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One-Pot Approach (one-pot + approach)
Selected AbstractsDiverse Asymmetric Quinolizidine Synthesis: A Stereodivergent One-Pot ApproachADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Wei Zhang Abstract A diverse stereodivergent organocatalytic one-pot addition/cyclization/annulation sequence to optically active quinolizidine derivatives from easily available starting materials is presented. The one-pot sequence relies on a pyrrolidine-catalyzed enantioselective conjugate addition of electron-deficient amide ,-carbons to ,,,-unsaturated aldehydes, spontaneous hemiaminal formation and acid-catalyzed/mediated N -acyliminium ion cyclization to give the quinolizidine framework. Simple tuning of the reaction conditions in the N -acyliminuim ion cyclization step provides a diastereomeric switch, which gives access to both of the two bridgehead epimers through kinetic, thermodynamic or chelation control. The methodology display a broad substrate scope that is demonstrated by the stereoselective formation of indolo-, thieno-, benzofuro-, furo- and different benzoquinolizidine derivatives with high atom efficiency, up to >99% ee and up to >95:5 dr. Due to its efficiency, synthetic diversity and operational simplicity, this protocol has the potential to find important use as a key step in natural product synthesis, biochemistry and pharmaceutical science. The stereochemical outcome of the one-pot sequence was investigated, and the mechanism and origin of stereoselectivity of the different steps is discussed. [source] Organocatalysis in Natural Product Synthesis: A Simple One-Pot Approach to Optically Active ,-DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Nikolaj Røjkjær Andersen Abstract Optically active ,-diols have been prepared using an organocatalytic one-pot approach from ,,,-unsaturated aldehydes using (E) -benzaldehyde oxime as nucleophile in an oxa-Michael reaction with subsequent in situ reduction or Grignard addition. With this protocol at hand, two biologically active compounds, an insect sex pheromone and a glycerol kinase substrate have been synthesized. [source] One-Pot Approach to Synthesize Star-Shaped Polystyrenes via RAFT-Mediated Radical CopolymerizationMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2007Qingchun Liu Abstract Previously, we have reported a one-pot approach to generate star-shaped polymers by copolymerization of a maleimide inimer or bismaleimide hexane (BMIH) and a large excess of styrene (St) via atom transfer radical polymerization. Herein, we extended this approach towards the synthesis of star polystyrene through reversible addition fragmentation chain-transfer (RAFT)-mediated radical copolymerization of BMIH and an excess of St with cumyl dithiobenzoate (CDB) as a chain-transfer agent (CTA). It was illustrated that the PS arms were grafted from the preformed core, which was formed in situ during the copolymerization of BMIH and St. Therefore, this facile one-pot approach can be performed by applying different type of controlled radical polymerization. However, linear PS still was generated as a byproduct which had been observed previously. [source] ChemInform Abstract: An Efficient One-Pot Approach to Phenanthrene Derivatives Using a Catalyzed Tandem Ullmann-Pinacol Coupling Reaction.CHEMINFORM, Issue 7 2009Shuan-zheng Lin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: An Efficient Three-Component One-Pot Approach to the Synthesis of 2,3,4,5-Tetrahydro-1H-2-benzazepines by Means of Rhodium-Catalyzed Hydroaminomethylation.CHEMINFORM, Issue 27 2008Tiago O. Vieira Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Organocatalysis in Natural Product Synthesis: A Simple One-Pot Approach to Optically Active ,-DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Nikolaj Røjkjær Andersen Abstract Optically active ,-diols have been prepared using an organocatalytic one-pot approach from ,,,-unsaturated aldehydes using (E) -benzaldehyde oxime as nucleophile in an oxa-Michael reaction with subsequent in situ reduction or Grignard addition. With this protocol at hand, two biologically active compounds, an insect sex pheromone and a glycerol kinase substrate have been synthesized. [source] One-Pot Approach to Synthesize Star-Shaped Polystyrenes via RAFT-Mediated Radical CopolymerizationMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2007Qingchun Liu Abstract Previously, we have reported a one-pot approach to generate star-shaped polymers by copolymerization of a maleimide inimer or bismaleimide hexane (BMIH) and a large excess of styrene (St) via atom transfer radical polymerization. Herein, we extended this approach towards the synthesis of star polystyrene through reversible addition fragmentation chain-transfer (RAFT)-mediated radical copolymerization of BMIH and an excess of St with cumyl dithiobenzoate (CDB) as a chain-transfer agent (CTA). It was illustrated that the PS arms were grafted from the preformed core, which was formed in situ during the copolymerization of BMIH and St. Therefore, this facile one-pot approach can be performed by applying different type of controlled radical polymerization. However, linear PS still was generated as a byproduct which had been observed previously. [source] A General Method for the Rapid Synthesis of Hollow Metallic or Bimetallic Nanoelectrocatalysts with Urchinlike MorphologyCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2008Shaojun Guo Abstract We have reported a facile and general method for the rapid synthesis of hollow nanostructures with urchinlike morphology. In-situ produced Ag nanoparticles can be used as sacrificial templates to rapidly synthesize diverse hollow urchinlike metallic or bimetallic (such as Au/Pt) nanostructures. It has been found that heating the solution at 100,°C during the galvanic replacement is very necessary for obtaining urchinlike nanostructures. Through changing the molar ratios of Ag to Pt, the wall thickness of hollow nanospheres can be easily controlled; through changing the diameter of Ag nanoparticles, the size of cavity of hollow nanospheres can be facilely controlled; through changing the morphologies of Ag nanostructures from nanoparticle to nanowire, hollow Pt nanotubes can be easily designed. This one-pot approach can be extended to synthesize other hollow nanospheres such as Pd, Pd/Pt, Au/Pd, and Au/Pt. The features of this technique are that it is facile, quick, economical, and versatile. Most importantly, the hollow bimetallic nanospheres (Au/Pt and Pd/Pt) obtained here exhibit an area of greater electrochemical activity than other Pt hollow or solid nanospheres. In addition, the ,6,nm hollow urchinlike Pt nanospheres can achieve a potential of up to 0.57,V for oxygen reduction, which is about 200,mV more positive than that obtained by using a ,6,nm Pt nanoparticle modified glassy carbon (GC) electrode. Rotating ring-disk electrode (RRDE) voltammetry demonstrates that ,6,nm hollow Pt nanospheres can catalyze an almost four-electron reduction of O2 to H2O in air-saturated H2SO4 (0.5,M). Finally, compared to the ,6,nm Pt nanoparticle catalyst, the ,6,nm hollow urchinlike Pt nanosphere catalyst exhibits a superior electrocatalytic activity toward the methanol oxidation reaction at the same Pt loadings. [source] | ||||||||||