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  • 1
    Electronic Resource
    Electronic Resource
    Aminyl oxides (nitroxides). 36. Formation of 3,7-dioxa-2,6-diazabicyclo[3.3.0]octanes by dimerization of vinyl aminyl oxides (vinyl nitroxides) (1984)
    s.l. : American Chemical Society
    The @journal of organic chemistry 49 (1984), S. 2654-2656 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00188a037
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  • 2
    Electronic Resource
    Electronic Resource
    Nitroxide (Aminyloxide), 43 Der Einfluß struktureller Faktoren auf die Dimerisierung von Vinylnitroxiden mit cyclischen Acylgruppen als β-Substituenten (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 513-521 
    Details
    ISSN: 0009-2940
    Keywords: Nitroxides, dimerization of / Vinyl nitroxides / 1,2-Oxazepines, 2,5,6,7-tetrahydro- / Nitrones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitroxides (Aminyl Oxides), 43. - The Effect of Structural Features upon the Dimerization of Vinyl Nitroxides Substituted in β-Position by Cyclic Acyl GroupsReaction between N-alkyl- and N-arylhydroxylamines and hydroxymethylene compounds 4 (derivatives of menthone, norboranone, borananone, indanone, and γ-butyrolactone) affords nitrones existing in the tautomeric forms 5 and 6. Oxidation of these nitrones generates the β-acylated vinyl nitroxides 7, which dimerize in various ways. The N-alkyl-substituted vinyl nitroxides 7DA, De, Ea, Ga, and Gf yield simple CC-bonded dimers 8 From 7Ba dimer 10 is formed via 8Ba. The structure of 10 is confirmed by an X-ray analysis. In contrast, the N-arylsubstituted vinyl nitroxides 7 Ab, Fc, and Bc as well as the N-alkyl-substituted 7 Aa afford the bicyclic dimers 9 which arise by OC dimerization followed by an intramolecular 1,3-dipolar cycloaddition. Finally, the vinyl nitroxides 7Dc and Dd underwent further oxidation to give dehydrodimers 12. 12e is formed only if 6De is oxidized by a large excess of lead dioxide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230318
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  • 3
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XXXV. Das tricyclische Dimere eines Vinylaminyloxids (Vinylnitroxids) und seine Isomerisierung zu einem 2,4,7,9-Tetraoxa-5,10-diazatetracyclo[4.4.2.03,12. 08,11]dodecan (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2615-2621 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxides (Nitroxides), XXXV. The Tricyclic Dimer of a Vinyl Aminyl Oxide (Vinyl Nitroxide) and its Isomerization to give a 2,4,7,9-Tetraoxa-5,10-diazatetracyclo[4.4.2.03,12.08,11]dodecaneVinyl aminyl oxide 6 is formed by oxidation of hydroxylamine 3 via the intermediates 4 and 5. Dimerization of 6 yields the tricyclic compound 8. In solution dissoziation of 8 occurs at approximately 40°C, four bonds being cleaved to afford radical 6. By prolonged heating in various solvents as well as by proton catalysis at room temperature 8 is rearranged to give the tetracyclic isomer 9, the structure of which has been confirmed by X-ray analysis.
    Notes: Das Vinylaminyloxid 6 entsteht bei der Oxidation des Hydroxylamins 3 über die Zwischenstufen 4 und 5. 6 dimerisiert unter Bildung der tricyclischen Verbindung 8. 8 dissoziiert in Lösung bereits bei etwa 40°C unter Spaltung von vier Bindungen in das Radikal 6. Durch längeres Erhitzen in verschiedenen Lösungsmitteln, aber auch unter Protonenkatalyse bei Raumtemperatur, wird 8 in ein tetracyclisches Isomeres 9 umgewandelt. Die Struktur von 9 wurde durch Röntgenstrukturanalyse ermittelt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170806
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese homochiraler 3-Oxa-2,7-diazabicyclo[3.3.0]octane aus Aminosäuren durch intramolekulare 1,3-dipolare Cycloaddition von Nitronen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 787-795 
    Details
    ISSN: 0009-2940
    Keywords: Heterobicyclo[3.3.0]octanes, homochiral ; Amino acids ; Nitrones ; Cycloadditions, diastereoselective, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Homochiral 3-Oxa-2,7-diazabicyclo[3.3.0]octanes from Amino Acids by Intramolecular 1,3-Dipolar Cycloaddition of NitronesN1-Allylamino alcohols 9 were prepared from amino acids by various methods. Swern oxidation of 9 afforded aldehydes 11. By reaction of 11 with N1-alkylhydroxylamines nitrone intermediates 4 were formed which spontaneously underwent an intramolecular 1,3-dipolar cycloaddition to yield the bicyclic compounds 6. The cycloaddition proceeds diastereoselectively furnishing homochiral compounds 6 from homochiral starting materials. The structure of 6aA was confirmed by X-ray structural analysis.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260333
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  • 5
    Electronic Resource
    Electronic Resource
    Intramolekulare Cycloaddition von Nitronen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1999-2014 
    Details
    ISSN: 0009-2940
    Keywords: Nitrones ; Cycloaddition, intramolecular ; Heteroanaloga of bicyclo[3.3.0]octanes, bicyclo[4.3.0]nonanes and bicyclo[4.2.1]nonanes ; γ-Amino alcohols, heterocyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecular Cycloaddition of NitronesNitrones 9 and 10, formed by treatment of the corresponding aldehydes with N-substituted hydroxylamines, are converted into the cis fused bicyclic compounds 11 and 12, respectively. While this intramolecular cycloaddition as a rule occurs at room temperature, the formation of compounds 17/18 and/or 20/21 from the corresponding nitrones needs refluxing in toluene with exception of 17Ca. The N-aryl-substituted nitrones 14C/15C form dimers 22C/23C spontanously at room temperature. However, dimerization is reversible; thus 22/23C afford the bicyclic compounds 17/18 and/or 20/21 on heating in toluene via the corresponding nitrone intermediates.  -  Hydrogenation cleaves isoxazolidine ring of the bicyclic compounds. Thus, 17Ca and 18Ca yield the hexahydrothiepine 27C and oxepane derivatives 28C, respectively, 21Ca gives the tetrahydropyran 30C. Diastereomerically pure 29C arises by prolonged hydrogenation of 17Ca under reinforced conditions via 27C.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231011
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  • 6
    Electronic Resource
    Electronic Resource
    Bicyclic and Tricyclic Compounds with β-Amino Alcohol Groups as Chiral Ligands in the Enantioselective Reaction of Diethylzinc with Aldehydes (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 423-434 
    Details
    ISSN: 0947-3440
    Keywords: 3,7-Dioxa-2-azabicyclo[3.3.0]octanes ; 2,6-Dioxa-3-azatricyclo[5.3.1.04.11]undecanes ; Amino alcohols ; Chiral ligands ; Enantioselective catalysis ; Homogenous catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduction of the enantiomerically pure allyloxy esters 9 or ent-9 with DIBAH afforded the corresponding aldehydes which were treated in situ with chiral or achiral hydroxylamines 8 to give nitrones 10. These underwent a spontaneous intramolecular 1,3-dipolar cycloaddition, affording the bicyclic compounds 11 and 12, respectively. In an analogous manner, a mixture of the tricyclic compounds 14 and 15 was prepared. Treatment of compound 16 with cyclohexene oxide afforded a mixture of diastereomers 17 and 18. Diastereomers 14 and 15 as well as 17 and 18 could be separated by chromatography. X-ray analyses of compounds 11Ff, 17, and 11Af · HCl were performed. The bicyclic and tricyclic compounds were used as chiral ligands in the reaction of diethylzinc with aldehydes 19, in particular with benzaldehyde (19a). Using bicyclic compounds with a tertiary β-hydroxyalkyl substitutent at the N atom as ligands, ee's in the range of 78 to 95% were found. Whereas for the best ligands 11Ae and Af the enantioselectivity in the reaction of 4-tolualdehyde was only slightly decreased, with the aliphatic aldehydes 19c and d distinctly lower enantioselectivities were determined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970222
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  • 7
    Electronic Resource
    Electronic Resource
    Formation of tricyclic compounds in domino reactions of alkenal oximes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1649-1653 
    Details
    ISSN: 0947-3440
    Keywords: 9-Oxa-3-thia-10-azatricyclo[6.2.1.04,10]undecanes, 6-heteroatom-substituted ; 3-Thiazoline N-oxides ; Mercaptoacetaldehyde ; 1,3-Dipolar cycloadditions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Alkenal oximes 4, 12, and 13 were prepared by various methods. These oximes undergo a domino reaction with mercaptoacetaldehyde (1-M) affording tricyclic compounds 6, 17 and 18, respectively. At first the mercapto group adds to the oxime function forming a hydroxyamino moiety which then condenses with the aldehyde group giving the cyclic nitrones 10, 15, and 16, resp., as intermediates. These nitrones undergo spontaneously an intramolecular cycloaddition yielding the tricyclic compounds (6, 17, 18). The regioselectivity of the latter reaction step is opposite to that observed for corresponding intermolecular nitrone cycloadditions. The domino reaction proceeds highly selectively affording only one of the diastereomers. Starting from enantiomerically pure oxime 13, we prepared optically active 18. The stereogenic center of 13 induces the formation of three further stereogenic centers in the product. The configuration at C-5 of 18 was determined by a NOESY experiment.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199509229
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  • 8
    Electronic Resource
    Electronic Resource
    An Intramolecular 1,3-Dipolar Cycloaddition Involving One Alkyne and Two Nitrone Groups (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 469-471 
    Details
    ISSN: 0947-3440
    Keywords: Cycloadditions ; Asymmetric Synthesis ; Heterocycles ; Alkynes ; Reductions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral nonracemic compound 4 was prepared from ethyl (S)-(-)-lactate and 1,4-dibromo-2-butyne. Reduction with DIBAH at -72°C and subsequent treatment of the resulting dialdehyde with N-methylhydroxylamine yielded the dinitrone 5, which underwent two consecutive intramolecular cycloadditions to give the chiral nonracemic compound 7. The structure of 7 was confirmed by an X-ray analysis. Reductive ring opening afforded compound 8.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970306
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  • 9
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XXXIII. Oxidative Kupplung von Aminen und Hydroxylaminen mit Nitronen. Die Stereochemie von (Aminoalkyl) aminyloxiden (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2431-2439 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxide (Nitroxide), XXXIII. Oxidative Coupling of Amines and Hydroxylamines with Nitrones. The Stereochemistry of (Aminoalkyl)aminyl OxidesOn treatment of nitrones 1 and 5 with amines 2 an equilibrium arises with 3 and 6, respectively. Oxidation with lead dioxide affords the (aminoalkyl)aminyl oxides 4 and 7, which were detected by ESR spectroscopy. According to the coupling constants radical 4Ag prefers conformation K1, whereas a dynamic equilibrium between K2 and K3 exists for 4Aa, Ae and Af. For 4Aa the barrier of interconversion has been found to be 4.1 ± 0.5 kcal/mol. Radicals 4B, C and D prefer conformations similar to K4 or K5. The center of chirality in 4Ca and Cc is responsible for the different coupling constants of the two benzylic protons at the other side of the aminyl oxide group.
    Notes: Die bei Einwirkung der Amine 2 auf die Nitrone 1 und 5 im Gleichgewicht mit den Edukten vorliegenden Addukte 3 und 6 wurden mit Bleidioxid zu den (Aminoalkyl)aminyloxiden 4 und 7 oxidiert, die ESR-spektroskopisch nachgewiesen werden. Nach den Kopplungskonstanten bevorzugt 4Ag die Konformation K1, während bei 4Aa, Ae und Af ein dynamisches Gleichgewicht zwischen K2 und K3 besteht. Die Umwandlungsbarriere K2 ⇌ K3 beträgt 4.1 ± 0.5 kcal/mol bei 4Aa. Für 4B, C und D wurden die Vorzugskonformationen abgeleitet, die zwischen K4 und K5 liegen. In 4Ca und Cc bedingt das Vorliegen eines Chiralitätszentrums unterschiedliche Kopplungskonstanten für die beiden Benzylprotonen auf der anderen Seite der Aminyloxidgruppe.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140710
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  • 10
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XXXIV. Amidinyl-N-oxide und -N,N′-dioxide als Sekundärradikale bei der oxidativen Kupplung von Aminen und Hydroxylaminen mit Nitronen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2440-2449 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxide (Nitroxide), XXXIV. Amidinyl-N-Oxide and N,N′-Dioxides as Secondary Radicals in the Oxidative Coupling of Amines and Hydroxylamines with NitronesAminyl oxides 3, formed by oxidation of a mixture of nitrones 1 and primary amines 2, are converted into the secondary radicals 4 with increasing reaction time. In addition to dehydrogenation of 3 elimination of R2H is observed, starting with nitrones 1B-E. Radicals 10 and subsequently 4Ae arise from 1A and N-tert-butylhydroxylamine (15), but 17 is detected, too; from the reaction mixture the lead complexe 14 can be isolated. Oxidative coupling of 2 with cyclic nitrones 20 and 28, respectively, affords aminyloxides 23 and 29 via their primary radicals. Further oxidation gives 24 and 30, respectively. From this reaction the lead complexes 25 can be isolated.
    Notes: Die bei der Oxidation von Gemischen aus Nitronen 1 und primären Aminen 2 gebildeten Aminyloxide 3 werden bei längerer Reaktionsdauer in Sekundärradikale 4 umgewandelt. Mit den Nitronen 1B-E tritt neben der Dehydrierung von 3 noch eine Eliminierung von R2H auf. Aus 1A und N-tert-Buthylhydroxylamin (15) entstehen die Radikale 10 und anschließend 4Ae, daneben wird auch 17 beobachtet; aus dem Reaktionsgemisch kann der Bleikomplex 14 isoliert werden. Die oxidative Kupplung von 2 mit den cyclischen Nitronen 20 bzw. 28 ergibt über die Primärradikale die Aminyloxide 23 bzw. 29, die weiter zu 24 bzw. 30 oxidiert werden können. Bei dieser Reaktion lassen sich die Bleikomplexe 25 isolieren.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140711
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