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1Author    S.Requires cookie*
 Title    Silaheterocyclen, XXXIII [1, 2]: Cycloadditions-Reaktionen des 1.1-Dichlor-2-neopentyIsilaethens mit Pentafulvenen  
 Abstract    ilaheterocycles, X X X III [1, 2]: C y c lo a d d itio n R e a c tio n s of 1 .1 -D ic h lo ro -2 -n eo p e n ty lsilen e w ith P e n ta fu lv e n e s N o rb e rt A u n er* , C la u s-R ü d ig e r H e ik e n w ä ld e r The reaction between in situ formed l,l-dichloro-2-neopentyl-l-silene, Cl2Si=CHCH2rBu (2), and 1,1-dimethylpentafulvene (5) leads to the formation of exo/endo-isomeric [4+2] cy-cloadducts 9 and [2+2] stereoisom ers 10 in good yields. NMR spectroscopic investigations of the product mixture prove the different modes of the silene cycloaddition reactions ([4+2] vs [2+2] addition). Treatment of 9 and 10 with LiA lH 4 and LiMe yield the stereo-and regioisomeric derivati­ ves (LiAlH 4: 16. 17; MeLi: 18, 19), whereas PhMgBr reacts with 10 to give only the mono substitution, the [4+2] com pound 20, and the diphenylated silacyclobutane 21. The reactions of silene 2 with pentafulvenes 6 -8 lead to similar results. 
  Reference    Z. Naturforsch. 52b, 500—514 (1997); eingegangen am 19. Dezember 1996 
  Published    1997 
  Keywords    Cycloaddition Reactions, Neopentylsilene, Pentafulvenes, NMR Spectra 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-0500.pdf 
 Identifier    ZNB-1997-52b-0500 
 Volume    52 
2Author    Hans Möhrle, Heinz DwuletzkiRequires cookie*
 Title    Lactamacetale als potentielle Enamin-Synthone in Heterocyclensynthesen 3. Mitteilung: Das Sarkosinanhydrid-monoIactamacetal-System in Cycloadditionsreaktionen Lactam Acetals as Potential Enamine Synthons in Heterocyclic Synthesis 3rd Communication: The Sarcosinanhydride-monolactamacetal System in Cycloaddition Reactions  
 Abstract    Sarcosinanhydride-monolactamacetal (7) furnishes an equilibrium concentration of the elec-tronically activated tetrahydropyrazine 3b which yields in contrast to other pyrazine derivatives with 4-nitrophenylazide (4) the cycloaddition product 9. Catalytic cleavage of 9 leads to the triazene compound 11. 
  Reference    Z. Naturforsch. 42b, 229—232 (1987); eingegangen am 26. September 1986 
  Published    1987 
  Keywords    Lactam Acetals, Heterocyclic Synthesis, Cycloaddition Reactions, Triazene 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0229.pdf 
 Identifier    ZNB-1987-42b-0229 
 Volume    42 
3Author    Hans Möhrle, Heinz DwuletzkiRequires cookie*
 Title    Einstufen-Synthese des y-Carbolingerüsts durch Diels-Alder-Reaktion von Indol-"Keten-N,0-acetalen" Lactam Acetals as Potential Enamine Synthons in Heterocyclic Synthesis, 4th Communication One Step Synthesis of the y-Carboline Frame via Diels-Alder Reaction of Indol-"K etene-N .O -A cetals"  
 Abstract    2-Alkoxy-indoles 2a, b can be regarded as cyclic ketene-N .O -acetals. Their regiospecific [4+2]-Diels-A lder reaction with inverse electron dem and with the triazine 3 yield in a one step addition the y-carboline (4). 
  Reference    Z. Naturforsch. 42b, 1032—1034 (1987); eingegangen am 5. März 1987 
  Published    1987 
  Keywords    Lactam A cetals, Heterocyclic Synthesis, Cycloaddition Reactions, y-Carbolines 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-1032.pdf 
 Identifier    ZNB-1987-42b-1032 
 Volume    42 
4Author    RichardP. Kreher, Thomas HildebrandRequires cookie*
 Title    Structure and Reactivity of Isoannellated Heterocyclic Systems with 4nji-and (4/7+2);r-Electrons, XIV [1] Tri-and Tetracyclic Hetarenes with Localized or Delocalized Pyrrole Units  
 Abstract    2,7-Di-/er/-butyl-2,7-dihydro-benzo[ 1,2-c:3,4-c']dipyrrole (2b) and 2,5,8-Tri-rm-butyl-5.8-di-hydro-2H-benzo[l,2-c:3,4-c':5,6-c"]tripyrrole (3b) have been prepared by acetolysis of the cor-responding tri-and tetracyclic N-oxides, isolated in crystallinic form and characterized by spec-troscopic data. The scope of the N-oxide route is documented and the existence of benzo-annellated pyrroles is proofed. The stabilizing effect of the tert-butyl group is presumably sup-ported by the vicinal annellated heterocycles. 
  Reference    (Z. Naturforsch. 43b, 125—131 [1988]; eingegangen am 15. September 1987) 
  Published    1988 
  Keywords    Benzo-annellated Di-and Tripyrroles, Synthesis, Isolation, Spectroscopic Properties, Cycloaddition Reactions 
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 TEI-XML for    default:Reihe_B/43/ZNB-1988-43b-0125.pdf 
 Identifier    ZNB-1988-43b-0125 
 Volume    43 
5Author    Dieter LentzRequires cookie*
 Title    Cycloadditionsreaktion von Trifluorm ethylisocyanid an Diphenylethin Cycloaddition Reaction o f Trifluoromethyl Isocyanide to Diphenyl Ethyne  
  Reference    Z. Naturforsch. 47b, 148—150 (1992); eingegangen am 8. Juli 1991 
  Published    1992 
  Keywords    Trifluoromethyl Isocyanide, Cycloaddition Reaction, l, 2-Diphenyl-3, 4-bis(trifluoromethylimino)-cyclo-butene Crystal Structure 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0148_n.pdf 
 Identifier    ZNB-1992-47b-0148_n 
 Volume    47 
6Author    N. Orbert Auner, Erika PenzenstadlerRequires cookie*
 Title    Silaheterocyclen, XIII Erzeugung und Cycloadditionsverhalten von l,3-Diaza-2,4-disila-unj 1.3-Disilacyclobutanen mit exocyclischer SiC-Doppelbindung Silaheterocycles, XIII Form ation and Cycloaddition Reactions of l,3-Diaza-2,4-disila-and 1.3-Disilacyclobutanes Containing an Exocyclic SiC Double Bond  
  Reference    Z. Naturforsch. 47b, 217 (1992); eingegangen am 16. Juli/19. August 1991 
  Published    1992 
  Keywords    Silaheterocycles, Synthesis o f l, 3-Diaza-2, 4-disilacyclobutane, Form ation o f Silenes, Cycloaddition Reactions 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0217.pdf 
 Identifier    ZNB-1992-47b-0217 
 Volume    47 
7Author    N. Orbert Auner, Erika Penzenstadler, Eberhardt HerdtweckRequires cookie*
 Title    Silaheterocyclen, XX Aminosubstituierte Vinylchlorsilane und Silaethene: Bausteine zur Synthese von l,3-Diaza-2-silacyclopentanen [1] Silaheterocycles, XX Am inosubstituted Vinylchlorosilanes and Silenes: Building Blocks for the Synthesis of l,3-Diaza-2-silacyclopentanes [1]  
 Abstract    The amino-substituted vinylchlorosilanes 4 -7 are synthesized from N ,N ,N '-trim ethyl-ethylenediamine (8 a) or tris(trimethylsilyl)ethylenediamine (8 b), LiBu" and organodichloro-vinylsilanes. 5 eliminates trimethylchlorosilane when distilled and yields 1,3-diaza-2-silacyclopentane 9, whereas the com pounds 6 and 7 show a great tendency to oligomerize. The reaction o f 4 with LiBu1 gives a neopentylsilene intermediate 10 a which can be trapped by isoprene or 1,3-butadiene yielding small amounts o f the Diels-Alder products 11 and 12, re­ spectively. The main reaction pathway for 10 a is rearrangement with migration o f a M e3Si-group from nitrogen to the silene's carbon atom and a new N —Si bond formation to give the diazasilacyclopentane 10 which has been characterized by X-ray diffraction analysis. This in­ tramolecular rearrangement appears to involve a pentacoordinated silene Si-atom. N o dimer-isation o f 10a to a disilacyclobutane is observed. The introduction o f a second Si-tris(tri-methylsilyl)ethylenediamine substituent at the SiC frame work does not result in silene stabili­ sation: there is no evidence for Si-hexacoordination in silene 15 nor in the [4+2] cyclo-addition product with isoprene (14). 
  Reference    Z. Naturforsch. 47b, 1377—1385 (1992); eingegangen am 6. Mai 1992 
  Published    1992 
  Keywords    Silaheterocycles, Synthesis, Form ation o f Silenes, Cycloaddition Reactions, Highly C oordinated Silicon 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-1377.pdf 
 Identifier    ZNB-1992-47b-1377 
 Volume    47 
8Author    RichardP. Kreher, Gerald Dyker, WilhelmP. NeumannRequires cookie*
 Title    Structure and Reactivity of Isoannelated Heterocyclic Systems with Ann-and (4n+2)jr-Electrons, XII [1] 2-terr-Butyl-4-methyl-2,4-dihydropyrrolo[3,4-b]indoles: Tricyclic Hetarenes with Isoannelated Pyrrole Rings  
  Reference    Z. Naturforsch. 42b, 473—477 (1987); eingegangen am 14. November 1986 
  Published    1987 
  Keywords    Substituted 2, 3-Dihydropyrrolo[3, 4-b]indoles, Synthesis, Isolation, Spectroscopic Properties, Cycloaddition Reactions 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0473.pdf 
 Identifier    ZNB-1987-42b-0473 
 Volume    42 
9Author    N. Orbert Auner, Erika PenzenstadlerRequires cookie*
 Title    Silaheterocyclen, XVII Synthese und Cycloadditionsreaktionen neuartiger, aminocyclischer Silaethene [1] Silaheterocycles, XVII Synthesis and Cycloaddition Reactions of Novel Amino Cyclic Silenes [1]  
 Abstract    The silene 2 is formed by reacting 2-chloro-l,3-bis(trimethylsilyl)-2-vinyl-1,3-diaza-2-silacyclopentane (5) with LiBu' in «-pentane in the tem perature range from -1 0 to +10 °C. The reaction primarily leads to the corresponding a-lithio adduct 6 by addition of the Li-organyl to the vinyl group o f 5; subsequent 1,2-LiCl elimination yields 2 as an intermediate. 2 can be trapped by polar reagents M e3SiX (X = OMe, 0 S 0 2C F 3) as well as by organic dienes which add across the Si = C bond; in the absence of trapping agents, trisilacyclohexane 7 is isolated. The cycloaddition behaviour of 2 is best described by the two mesomeric formulae (a) and (ß), with competitive [4+2] and [2 + 2] addition routes: While with butadienes and norbor-na-2,5-diene the [2 + 2] products are formed mainly in a multiple step reaction via zwitterionic intermediates (1,4 dipoles), the ratio o f the [4+2]/[2 + 2] derivatives from 2 and cyclohexa-1,3-diene becomes nearly equivalent. 2 is thus quite com parable in its reactivity to dichloro-neopentylsilene, Cl2Si = C H C H 2Bu'. 
  Reference    Z. Naturforsch. 47b, 795—804 (1992); eingegangen am 25. November 1991 
  Published    1992 
  Keywords    Silaheterocycles, Synthesis, 1, 3-Bis(trimethylsilyl)-1, 3-diaza-2-silacyclopentane, F orm ation o f Silenes, Cycloaddition Reactions 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0795.pdf 
 Identifier    ZNB-1992-47b-0795 
 Volume    47 
10Author    Norbert Auner, Carola Wagner, Wolfgang ZieheRequires cookie*
 Title    Silaheterocyclen, XXVII. Substituenteneffekte zur Steuerung des Cycloadditionsverhaltens von Silaethenen [1] Silaheterocycles, XXVII. Controlling the Cycloaddition Behavior of Silenes by Substituent Effects [1]  
 Abstract    The silene Cl2Si=C(Ph)CH2Bu' (2) is formed by the reaction o f l,l,l-trichloro-2-phenyl-l-silaprop-2-ene (1) with LiBu' in n-pentane in the temperature range from -1 5 to 0 °C. TTie reaction initially leads to the corresponding a-lithio adduct A (addition o f LiBu' to the vinyl group of 1); subsequent LiCl elimination yields 2 as an intermediate. 2 can be trapped by Me3SiOMe (3) and dienes which add across the Si=C bond. In the absence of trapping agents but in the presence of the Lewis base N E t3 the mixture 1/LiBu' reacts to give the disilacyclobutane 4. Due to its electronic and steric properties, Cl2Si=C(Ph)C H 2Bu' (2) and butadienes yield mainly the D iels-A lder adducts (5, 7, 9) while with styrene and 1,3-cyclo-hexadiene the [2 + 2] and [4 + 2] products are formed in competition. With 2-norbornene, 2,5-norbornadiene and quadricyclan the [2 + 2] and [2 + 2 + 2] products are formed selectively but only in low yields. In all reactions except with quadricyclan an ene-reaction com petes with the cycloaddition leading to ene-com pounds as by-products. 
  Reference    Z. Naturforsch. 49b, 831 (1994); eingegangen am 18. Februar 1994 
  Published    1994 
  Keywords    Silaheterocycles, l, l, l-Trichloro-2-phenyl-l-silaprop-2-ene, Substituent Effects, Formation of Silenes, Cycloaddition Reactions 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-0831.pdf 
 Identifier    ZNB-1994-49b-0831 
 Volume    49