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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 542-554 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cleavage of Unstrained CC Single Bonds in Tricarbonyliron Complexes of 5,5-Dialkyl-substituted CyclopentadienesCleavage of CC single bonds in η4-spirononadieneiron complex 9 is initiated by Fe2(CO)9 in boiling benzene, leading to the bridged (σ-alkyl-π-cyclopentadienyl)iron complex 10. By Fe2(CO)9 the latter is transformed to the dinuclear “propylfulvene complex” 16. The observed CC bond cleavage reactions of spirocyclopentadienes 6 can also be applied to monocyclic 5,5-dialkylcyclopentadienes 1. Crossover experiments and stereochemical results suggest an intramolecular reaction path and migration of the endo-alkyl group.
    Notes: Die Spaltung einer CC-Einfachbindung im η4-Spirononadieneisen-Komplex 9 wird durch Fe2(CO)9 in siedendem Benzol initiiert und führt zum überbrückten (σ-Alkyl-π-cyclopentadienyl)eisen-Komplex 10. Dieser reagiert - wiederum unter der Einwirkung von Fe2(CO)9 - weiter zum zweikernigen „Propylfulven-Komplex“ 16. Die an Spirocyclopentadienen 6 beobachteten Umwandlungen unter CC-Bindungsspaltung lassen sich auf offenkettige 5,5-Dialkylcyclopentadiene 1 übertragen. Aus Kreuzungsversuchen und stereochemischen Befunden kann ein intramolekularer Reaktionsverlauf unter Wanderung der endo-Alkylgruppe abgeleitet werden.
    Additional Material: 1 Tab.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 169-181 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regioselektive Synthese von substituierten Bicyclo[3.2.1]oct-3-en-2,8-dionen durch doppelte Carbonylierung von 1,3-CyclohexadienenDie zweifache Carbonylierung von 1,3-Cyclohexadienen 1 wird zur Synthese substituierter Bicyclo[3.2.1]oct-3-en-2,8-dione 4 angewandt. Die durch Lewissäuren herbeigeführte Ringerweiterung substituierter Cyclohexadienkomplexe 2 ergibt die Cycloheptanon-Alkyl-Allyl-Komplexe 3 mit hoher Regioselektivität. Substituierte bicyclische Diketone 4 werden in hohen Ausbeuten durch Behandeln der Komplexe 3 mit Kohlenmonoxide unter Druck oder durch oxidative Aufspaltung erhalten. Die beiden Carbonylierungsschritte können auch in einer Eintopfversion durchgeführt werden.
    Notes: Double carbonylation of 1,3-cyclohexadienes 1 is applied to the synthesis of substituted bicyclo[3.2.1]oct-3-ene-2,8-diones 4. The Lewis acid mediated ring enlargement of substituted cyclohexadiene complexes 2 produces the cycloheptanone alkyl allyl complexes 3 with high regioselectivity. Substituted bicyclic diketones 4 are obtained in high yields by treating the complexes 3 with carbon monoxide under pressure or by oxidative decomposition. The two carbonylation steps can also be performed in a one-pot version.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 151-158 
    ISSN: 0009-2940
    Keywords: Carbonylation of 1,4-dienes ; Catalysis, cobalt ; Catalysis, rhodium ; Cyclopentanone derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrocarbonylating Cyclization of Dienes, 5.1) - Model Experiments for the Synthesis of the Acorane Skeleton from substituted 1,4-DienesHeading towards the generation of the five-membered ring substitution pattern in the acorane skeleton (1) the hydrocarbonylating cyclization of various substituted 1,4-dienes 3 to cyclopentanones 4 and 5 was studied. While octacarbonyldicobalt as catalyst precursor nearly exclusively leads to linking of the less substituted carbon centers, the more active (cyclooctadiene)rhodium complex also effects the formation of new quaternary centers. The 1,5-dienes 15a-e converted under the same conditions revealed no tendency to isomerize to 1,4-dienes with the same carbon skeleton or to form analogous cyclization products. Finally, using the model substrate 3i the regio- and stereoselective synthesis of the cyclopentanone system 4i containing the same substitution pattern as the five-membered ring of the target molecule 1 can be accomplished.
    Notes: Mit dem Ziel der Erzeugung des Fünfringsubstitutionsmusters im Acorangerüst (1) wurde die hydrocarbonylierende Cyclisierung verschiedenartig substituierter 1,4-Diene 3 zu Cyclopentanonen 4 und 5 untersucht. Während beim Einsatz von Octacarbonyldicobalt als Katalysatorvorläufer weitgehend nur die Verknüpfung der weniger substituierten Kohlenstoffzentren der Diene eintritt, bewirkt der wirksamere (Cyclooctadien)rhodiumkomplex auch die Bildung neuer quartärer Zentren. Die unter den gleichen Bedingungen umgesetzten 1,5-Diene 15a-e zeigen keine Tendenz zur Isomerisierung zu 1,4-Dienen mit gleichem Kohlenstoffgerüst bzw. zur Ausbildung der entsprechenden Cyclisierungsprodukte. Mit dem Modellsubstrat 3i gelingt schließlich die regio- und stereoselektive Synthese des Cyclopentanonsystems 4i mit einem dem Fünfring des Zielmoleküls 1 entsprechenden Substitutionsmuster.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1669-1681 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Alkyls via Nucleophilic Cyclopropane Ring Opening in Spiro[2.4]hepta-4,6-diene with Sodium [Dicarbonyl(η5-cyclopentadienyl)ferrate]Reaction of spiro[2.4]hepta-4,6-diene (1a) and its methylated derivatives 1b and c with nucleophilic sodium [dicarbonyl(η5-cyclopentadienyl)ferrate] (2) leads to cyclopropane ring opening and formation of the substituted cyclopentadienes 4a-c containing iron alkyl side chains. These easily accessible bifunctional units may be modified at the cyclopentadiene ring as well as at the metal carbon bond to form various 1,1′-disubstituted ferrocenes and other transition metal complexes with functionalized side chains.
    Notes: Spiro[2.4]hepta-4,6-dien (1a) sowie seine methylierten Derivate 1b und c lassen sich durch das nucleophile Natrium-[dicarbonyl(η5-cyclopentadienyl)ferrat] (2) unter Öffnen des Dreirings in die substituierten Cyclopentadiene 4a-c mit Metallalkyl-Seitenketten umwandeln. Den so einfach zugänglichen bifunktionellen Baustein kann man sowohl am Cyclopentadienyl-Teil als auch an der Metall-Kohlenstoff-Bindung umwandeln und in verschiedenartige 1,1′-disubstituierte Ferrocene sowie andere Übergangsmetallkomplexe mit funktionalisierten Seitenketten überführen.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 825-839 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regio- and Stereoselectivity of the Hydrocarbonylating Cyclization of 1,4-Dienes with Carbon Monoxide: Synthesis of (±)-(α)-CuparenoneDirected towards the synthesis of the cuparene skeleton the hydrocarbonylating cyclization of 1,4-dienes 16, 27 to form cyclopentanones 17, 28 was tested for its regio- and stereoselectivity as well as the toleration of aryl groups in this cyclization method. Based on these results a new synthesis of (±)-(α)-cuparenone (29c) is developed.
    Notes: Die hydrocarbonylierende Cyclisierung von 1,4-Dienen 16, 27 zu Cyclopentanonen 17, 28 wurde mit dem Ziel der Synthese des Cuparengerüsts auf ihre Regio- und Stereoselektivität hin untersucht und die Tolerierbarkeit von Arylgruppen bei dieser Cyclisierung getestet. Darauf aufbauend wurde eine neue Synthese des (±)-(α)-Cuparenons (29c) entwickelt.
    Additional Material: 1 Tab.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2314-2329 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regio- and Stereoselectivity of the Metal-induced Ring Opening of Di- and Tetramethylspiro[2.4]-hepta-4,6-dienesMetal-induced ring opening of spiro[2.4]hepta-4,6-dienes was investigated using nickel, molybdenum, and iron carbonyls for 1,1-dimethyl- (4), 1,1,2,2-tetramethyl- (5), and the E- and Z-isomers of 1,2-dimethylspiro[2.4]hepta-4,6-diene (6). The reactions partially yielded labile product mixtures and therefore caused difficulties towards a clear interpretation of the results. While the products obtained with molybdenum and nickel carbonyls suggest a normal opening of the sterically less hindered cyclopropane bond and retention of configuration, the complexes found with iron carbonyls indicate a new, hitherto not observed reaction course involving cleavage of the exo-CC bond of the cyclopropane ring without retention of configuration.
    Notes: Die Regio- und Stereoselektivität der metallinduzierten Ringöffnung von Spiro[2.4]hepta-4,6-dienen wurde mit Nickel-, Molybdän- und Eisencarbonylen an 1,1-Dimethyl- (4), 1,1,2,2-Tetramethyl- (5) sowie an den E- und Z-Isomeren des 1,2-Dimethylspiro[2.4]hepta-4,6-diens (6) untersucht. Die Umsetzungen ergaben teilweise labile Produktgemische, die eine klare Interpretation der Resultate erschweren. Während die mit Molybdän- und Nickelcarbonylen erhaltenen Produkte auf eine normale Öffnung der sterisch weniger gehinderten Dreiringbindung und Konfigurationserhalt schließen lassen, geben die mit Eisencarbonylen gefundenen Komplexe Hinweis auf einen neuen, bisher nicht beobachteten Reaktionsverlauf über eine Öffnung der exo-CC-Bindung des Cyclopropansystems, die ohne Konfigurationserhalt verläft.
    Additional Material: 1 Tab.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 519-524 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrocarbonylating Cyclization of Dienes, 4.  -  Regio- and Stereochemistry of the Cobalt- and Rhodium-Catalyzed Synthesis of Substituted CyclopentanonesEffects of catalysts and of reaction conditions on the regio- and stereochemistry of hydrocarbonylating cyclization of 1,4-dienes to substituted cyclopentanones was studied. Via kinetic reaction control the formation of the thermodynamically unfavoured stereoisomers can be supported. Under certain reaction conditions exo-2-methylenecyclopentanones are formed instead of the saturated products, thus allowing the desired control of stereochemistry via succeeding hydrogenation.
    Notes: Die Einflüsse von Katalysatoren und Reaktionsbedingungen auf die Regio- und Stereochemie der hydrocarbonylierenden Cyclisierung von 1,4-Dienen zu substituierten Cyclopentanonen wurde untersucht. Durch kinetische Reaktionskontrolle läßt sich die Bildung der thermodynamisch ungünstigeren Stereoisomeren fördern. Unter bestimmten Reaktionsbedingungen werden statt der gesättigten Produkte exo-2-Methylencyclopentanone gebildet. Hierdurch wird die gewünschte Stereokontrolle durch nachfolgende Hydrierung möglich.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1063-1070 
    ISSN: 0009-2940
    Keywords: Carbonylation of 1,4-dienes ; Catalysis, cobalt and rhodium ; Cyclopentenone derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbonylating Cyclization of Dienes, 81. - Cyclization of 1,4-Dienes with Functional Groups in 3-Position1,4-Dienes 1a-i with functional groups at C-3 were synthesized and treated under the conditions of metal-catalyzed hydrocarbonylating cyclization. Under the usual conditions no cyclization products could be isolated. Modifications of the reaction conditions did not lead to the expected cyclopentanones of type 2 or 3 either. Instead, the original functional groups are split off. Depending on the reaction conditions, either the non-functionalized 2-cyclopentenones 5, the cyclopentanones 6, or the 2-cyclopentenones 7 with a functional group introduced from the solvent into the 2-methyl group are obtained. These unexpected products of type 7 at least formally correspond to allylic rearrangement products of the expected but not observed type-3 exo-methylenecyclopentanones. The mechanism of the formation of these products is discussed.
    Additional Material: 1 Tab.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1053-1061 
    ISSN: 0009-2940
    Keywords: Carbonylation of 1,4-dienes ; Cyclopentanone synthesis ; Catalysis, functional groups in ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbonylating Cyclization of Dienes, 71. - Cyclization of 1,4-Dienes Containing Functionalyzed Side Chains at C-3In order to test, whether functional groups are tolerable in rhodium- or cobalt-catalyzed hydrocarbonylating cyclizations of 1,4-dienes 1 to substituted cyclopentanones 2, various dienes of type 3 with functionalyzed side chains in C-3 were synthesized and treated under cyclization conditions. Ester, hydroxy, alkoxy, and acetate groups proved to be sufficiently stable (the latter only in rhodium-catalyzed conversions), so that the corresponding cyclopentanones 4 could be obtained in medium to good yields. Free carboxylic acid and aldehyde groups, however, prevented the formation of significant amounts of cyclization products. Pentenynes of type 6 under analogous conditions yielded at best only minor amounts of cyclopentanones.
    Additional Material: 3 Tab.
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 845-851 
    ISSN: 0009-2940
    Keywords: Cationic cycloheptadienyl iron complexes ; Eucarvone ; Nucleophilic attack ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic cycloheptadienyl iron complexes with new substitution patterns are generated by starting from the eucarvone complex 5 and the analogous triphenyl phosphite complex 6. These complexes are converted with different nucleophiles. Regioselectivity of the nucleophilic attack depends on the substitution pattern of the seven-membered ring. A new type of cationic system 7b, bearing an alkoxy substituent at C-1, was treated with nucleophiles leading to the ipso adducts of type 10. Unexpected attack at the central C-3 of the dienyl moiety is observed during the conversion of cationic complexes of type 9 with nucleophiles. The diene iron complexes, obtained in these reactions, can be converted to substituted cycloheptadienes by oxidative decomplexation, as shown by a selected example.
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