Verdazyls. Part 33. EPR and ENDOR studies of 6-oxo- and 6-thioxoverdazyls. X-Ray molecular structure of 1,3,5-triphenyl-6-oxoverdazyl and 3-tert-butyl-1,5-diphenyl-6-thioxoverdazyl

1993 ◽  
pp. 535 ◽  
Author(s):  
Franz A. Neugebauer ◽  
Hans Fischer ◽  
Claus Krieger
Keyword(s):  
Molecular Structure ◽  
X Ray ◽  
Tert Butyl

scholarly journals New Spiro-Tin Compounds: Reaction of N,N′-Dialkyl Sulfur Diimides with Cyclic Bis(amino)stannylenes - Unexpected Formation of a N-N Bond

1995 ◽  
Vol 50 (12) ◽  
pp. 1811-1817 ◽  
Author(s):  
Max Herberhold ◽  
Christian Köhler ◽  
Wolfgang Milius ◽  
Bernd Wrackmeyer
Keyword(s):  
Molecular Structure ◽  
Magnetic Resonance ◽  
Single Crystal ◽  
Structure Analysis ◽  
Membered Ring ◽  
Monoclinic Space Group ◽  
Unexpected Formation ◽  
Tin Compounds ◽  
X Ray ◽  
Tert Butyl

N,N′-Dialkyl sulfur diimides (1), R(NSN)R [R = Me (a), Et (b), nPr (c), nBu (d)] react with cyclic bis(amino)stannylenes such as 1,3-di-tert-butyl-4,4-dimethyl-1,3,4,2λ2-diazasilastannetedine (2) or 1,3-di-tert-butyl-4,4,5,5-tetramethyl-1,3,4,5,2λ2-diazadisilastannolidine (3) in a 2:1 ratio to give the new spiro-tin(IV) compounds 5a-d, 6b and 6c, built from the respective cyclic bis(amino)stannylene and a seven-membered ring in which the two sulfur diimide groups are coupled via a N-N bond and across the tin atom. A 1:1 adduct 4 is proposed as an intermediate which is the final product 4e in the case of R = tBu (1e). The products were characterized by multinuclear magnetic resonance (1H, 13C, 15N, 29Si, 119Sn NMR), and in the case of 5c the molecular structure was determined by single crystal X-ray structure analysis [monoclinic, space group C2/c ; a = 1504.1(3), b = 1393.3(3), c = 1688.6(3) pm; β = 115.71(3)°].

ChemInform Abstract: Dolastatins. Part 24. Synthesis of (-)-Dolastatin 10. X-Ray Molecular Structure of N,N-Dimethylvalyl-valyl-dolaisoleuine tert-Butyl Ester.

ChemInform ◽  
2010 ◽  
Vol 27 (33) ◽  
pp. no-no
Author(s):  
G. R. PETTIT ◽  
J. K. SRIRANGAM ◽  
S. B. SINGH ◽  
M. D. WILLIAMS ◽  
D. L. HERALD ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Butyl Ester ◽  
X Ray ◽  
Tert Butyl ◽  
Dolastatin 10

Behavior of 1,3-Di(tert-butyl)-2,4-bis(tetramethylpiperidino)-1,3,2,4-diphospha- diboretane towards Boron Halides and Adduct Formation of a Bicyclo[1.1.0]diphosphadiboretane with Tris(pentafluorophenyl)borane [1]

2006 ◽  
Vol 61 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Klaus Knabel ◽  
Heinrich Nöth ◽  
Robert T. Paine
Keyword(s):  
Molecular Structure ◽  
Structure Analysis ◽  
Adduct Formation ◽  
Ring System ◽  
Lewis Acidity ◽  
X Ray ◽  
Tert Butyl ◽  
Boron Halides ◽  
System 2

AbstractWhile the diphosphadiboretane (tBuP=Btmp)2, 1, reacts with boron trihalides BX3 (X = Cl, Br, I) with BN cleavage producing a number of unidentifiable products, a new tricyclic BP ring system 2, containing B3P3, PB2C2 and C6 rings, results from the combination of PhBCl2 and 1. B-Chlorocatecholborane and 1 give access to the diborylphosphane 3, tmpBCl-PtBu-cat (cat = C6H4O2B). This shows that the selectivity of the reactions increases as the Lewis acidity of boron halide decreases. The structure of compounds 2 and 3 were determined by X-ray structure analysis. The bicyclic (tmpBP)2 4 forms no adducts with MeI, CF3SO2Me or Ph3C(SnCl5). However, it adds B(C6F5)3 to give 10, the first BX3 adduct of this bicycle that is fully characterized including its molecular structure.

Dolastatins 24: synthesis of (–)-dolastatin 10. X-Ray molecular structure of N,N-dimethylvalyl-valyl-dolaisoleuine tert-butyl ester

1996 ◽  
pp. 859-863 ◽  
Author(s):  
George R. Pettit ◽  
Jayaram K. Srirangam ◽  
Sheo Bux Singh ◽  
Michael D. Williams ◽  
Delbert L. Herald ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Butyl Ester ◽  
X Ray ◽  
Tert Butyl ◽  
Dolastatin 10

The molecular structure of 4-tert-butylpyrazoles in the solid state and in solution: an X-ray, NMR and calorimetric study of the buttressing effect of a 4-tert-butyl substituent

2001 ◽  
Vol 25 (6) ◽  
pp. 819-823 ◽  
Author(s):  
Swiatoslaw Trofimenko ◽  
Arnold L. Rheingold ◽  
Louise M. Liable-Sands ◽  
Rosa María Claramunt ◽  
Concepción López ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Calorimetric Study ◽  
X Ray ◽  
Tert Butyl

scholarly journals Azaborolinyl-Komplexe, XV. Bis(η5-1,2-azaborolinyI)ruthenium-Sandwichkomplexe – Darstellung und Strukturuntersuchung/ Azaborolinyl Complexes, XV. Bis(η5-1,2-azaborolinyl)ruthenium Sandwich Complexes – Synthesis and Structure Investigation

1984 ◽  
Vol 39 (8) ◽  
pp. 1082-1087 ◽  
Author(s):  
Günter Schmid ◽  
Ottmar Boltsch ◽  
Dieter Bläser ◽  
Roland Boese
Keyword(s):  
Molecular Structure ◽  
Structure Investigation ◽  
X Ray Diffraction ◽  
Sandwich Complexes ◽  
Sandwich Complex ◽  
Interplanar Angle ◽  
X Ray ◽  
Tert Butyl ◽  
Complex Forms ◽  
Nmr Signals

AbstractThe synthesis of bis(1-tert-butyl-2 -methyl-η5 - 1 ,2 -azaborolinyl)ruthenium (1) and bis(2-methyll- trimethylsilyl-η5 - 1 ,2 -azaborolinyl)ruthenium (2) succeeds when RuCL is reacted with the corresponding 1,2-azaborolinyl lithium compounds in THF at -70 °C. Each of the sandwich complex forms two isomers with a clockwise and an anti-clockwise conformation of the azaborolinyl rings. The anti-clockwise isomer of 1 (1a ) gives colourless crystals which were investigated by singlecrystal X-ray diffraction methods. The molecular structure shows the rings in an eclipsed orientation forming an interplanar angle of 8.6 °. The isomers of 1 as well as of 2 give different 1H and 11B NMR signals.

Oxidation-Induced Acyl Group Transfer from Hydroquinone Esters to Nucleophiles

1998 ◽  
Vol 53 (7) ◽  
pp. 765-773 ◽  
Author(s):  
Gerald Reischl ◽  
Medhat El-Mobayed ◽  
Rudolf Beißwenger ◽  
Klaus Regier ◽  
Cäcilia Maichle-Mössmer ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Amino Acids ◽  
Chemical Oxidation ◽  
Acyl Transfer ◽  
X Ray ◽  
Group Transfer ◽  
Tert Butyl ◽  
X Ray Crystallography ◽  
Toluenesulfonic Acid ◽  
Mediated Oxidation

Bivalent oxidation of 3,5-di-tert-butyl-hydroquinone monoesters leads to phenoxenium ions, which can transfer an acyl group to nucleophiles. Based on this principle, dipeptides, glyco-amino acids and N-sulfonyl-amino acids were synthesized from hydroquinone esters of amino acids and p-toluenesulfonic acid. For this reaction, direct anodic and indirect mediated oxidation, as well as chemical oxidation with NBS or trisarylammoniumyl salts, was used. The mechanism of the acyl transfer is discussed in terms of a direct and/or a mediated process. A spirocyclic key intermediate was isolated and its molecular structure determined by X-ray crystallography.

Siliciumverbindungen mit starken intramolekularen sterischen Wechselwirkungen, XX [1] 1,1-Di-tert-butyl-2,2-dimesityldisilane: Synthese, Molekülstruktur, Radikale / Silicon Compounds with Strong Intramolecular Steric Interactions, XX [1] 1,1-Di-tert-butyl-2,2-dimesityldisilanes: Synthesis, Molecular Structure, Radicals

1985 ◽  
Vol 40 (5) ◽  
pp. 601-606 ◽  
Author(s):  
Manfred Weidenbruch ◽  
Klaus Kramer
Keyword(s):  
Molecular Structure ◽  
Radical Anion ◽  
Alkali Metals ◽  
Force Field Calculations ◽  
Silicon Compounds ◽  
X Ray ◽  
Tert Butyl ◽  
Anti Conformation ◽  
Empirical Force Field ◽  
Empirical Force Field Calculations

The sterically congested disilanes tBu2XSiSiXMes2 [X = H (1), X = Cl (2)] have been prepared. An X-ray structure analysis of 1 reveals a preference for the anti-conformation in the solid state. Similar results have been obtained by empirical force field calculations and DNMR spectroscopy. Reaction of 2 with an electron rich olefin leads to a chlorine bridged disilanyl radical whereas treatment with alkali metals yields the corresponding disilenyl radical anion, tBu2Si=SiMes2˙̄.

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